Allah's Preservation of the Sunnah
by Jamaal al-Din Zarabozo
Introduction: The Sunnah and Its Place in Islam
The Sunnah refers to the actions, statements and way of life of the Prophet Muhammad, may the blessing and mercy of Allah be upon him. It is an essential aspect of the entire system of Islam. Allah Himself in the Qur'an has ordered Muslims to take the Prophet as their role model and to listen and obey his words. The Sunnah is the ultimate normative practical expression of Islam. It is also the definitive explanation of the Qur'an itself. Without it there can be no true understanding of how to implement Islam.
The Prophet's Sunnah was preserved in what is known as the hadeeth literature. The question of the preservation of the Sunnah and the hadeeth is actually an issue concerning the preservation and purity of the religion of Islam itself. This issue becomes even more important given the fact that, unfortunately, many have a false conception of how the hadeeth were preserved and, therefore, they do not possess full confidence in the authenticity of the hadeeth of the Prophet.
Some of the Means by Which Allah Preserved the Sunnah
Allah, through humans, used many means by which He preserved the Sunnah. Some of these aspects are unique to the Muslim nation. Most importantly, these means of preservation were followed from the earliest times, without any interval available for the original material and sayings to be lost.
Some of the factors and means that contributed to the preserving of the Sunnah include the following:
The Companions' Understanding of Their Heavy Responsibilities
It is clear in the Qur'an that the earlier peoples had distorted, tampered and generally failed to minutely preserve the message that they received. The Companions of the Prophet understood that the Prophet Muhammad was the final messenger sent for humankind and that the task of preserving his teachings would fall upon their shoulders. It was up to them to make sure that what happened to the previous prophets' teachings would not happen to the Prophet Muhammad's message. Additionally, the Prophet himself impressed upon them the fact that they had the responsibility of taking from the Prophet and conveying to others. For example, the Prophet told them, in front of the throngs of the people at the time of pilgrimage:
"Let the one who is present inform the one who is absent. Perhaps the one who is present may convey it to one who can grasp it more than he can." (Saheeh Al-Bukhari, Saheeh Muslim)
This instruction from the Prophet can be seen in a number of his statements, some of which have been narrated from numerous Companions. For example, the Prophet said:
"May Allah make radiant the man who has heard what I said and has preserved it in his memory until he conveys it to another. Perhaps the one he conveyed it to has a better understanding than him."
The Prophet also warned them in a very stern fashion about conveying anything from him which may not be correct. Using the Arabic word kadhab, which in the dialect of the Prophet did not mean "to lie" but meant to convey something which is not correct, the Prophet stated:
"Convey from me, even if it is just a verse. And narrate [stories] from the Tribes of Israel and there is no harm. And whoever falsely attributes something to my authority shall take his own seat in the Hell-fire." (Saheeh Al-Bukhari)
It seems that the Prophet stated that warning on a number of occasions, as those words have been recorded from the Prophet by over fifty Companions.
Thus, the Companions realized that they had to be very careful in their narratives. They understood the warning stated above concerning one who falsely attributes something to the Prophet as applying to one who does so intentionally as well as unintentionally. In a report recorded in Sahih al-Bukhari, the Companion al-Zubair was asked why he did not narrate as many hadeeth as some of the others did. He replied, "As for me, I never parted from him [that is, the Prophet]. However, I heard him say, 'Whoever falsely attributes something to me shall take his own seat in the Hell-fire.'" Commenting on this statement, ibn Hajar noted that al-Zubair was obviously not speaking about himself forging something in the Prophet's name. Instead, he feared that if he narrated a lot, he would make mistakes. And those mistakes would put him under the warning mentioned in that hadeeth.
Anas ibn Maalik also said, "If I did not fear that I may make a mistake, I would narrate to you some of the things I heard from the Messenger of Allah. However, I heard him say, 'Whoever falsely attributes something to my authority shall take his own seat in the Hell-fire.'" This, once again, implies that Anas, a Companion, understood that the threat stated in that hadeeth also applies to the one who makes unintentional mistakes while narrating hadeeth.
In reality, some of the Companions, like Abu Hurairah, continued to study and memorize the hadeeth they learned from the Prophet. Therefore, they did not have as much to fear with respect to making mistakes. On the other hand, those who were not dedicated to such study had more to fear because their memories may fail them when they narrated from the Messenger of Allah.
The Recording of Hadeeth
Before discussing this topic, it should be noted that, in order for something to be preserved, it is not a necessary condition that it be recorded or written down. That is, simply because something was not written down, it does not mean that it was not accurately and correctly preserved. Furthermore, the writing of something down itself is not sufficient for the preservation of something. It is possible that something is recorded incorrectly. Both of these points were duly noted by the scholars of hadeeth. They did not require hadeeth to be written down for them to be accepted although they did recognize the importance of such a physical recording and many times, depending on the personality involved, preferred the written record over the verbal record. These scholars also realized that the mere recording of something is not sufficient. It must also be ascertained that it was recorded properly. Hence, scholars of hadeeth would accept or prefer written reports of scholars over memorized reports only if it was known that those scholars were proficient and correct in their writing.
It has been one of the favorite practices of many of the Orientalists to constantly state the "fact" that hadeeth were not recorded at first but were, instead, passed on only orally for the first two centuries after the Hijrah (Arabic calendar). Therefore, hadeeth are not much more than folklore and legend that was passed on orally and in a haphazard fashion for many years. Unfortunately, this is a misconception that has become quite widespread amongst many who have sufficed with a mere shallow research of the subject. In reality, this false claim and incorrect view has, by the grace of Allah, been refuted by numerous Muslim scholars in various doctoral dissertations in the Muslim world as well as at Western Universities, such as the dissertations of Muhammad Mustafa Azami (1967), published as Studies in Early Hadeeth, and Imitiyaz Ahmad's The Significance of Sunna and Hadeeth and their Early Documentationfrom Edinburgh in 1974.
The recording of the hadeeth of the Prophet, may Allah exalt/honor his position, began during the time of the Prophet himself. Al-Baghdaadi records a number of hadeeth that show that the Prophet explicitly allowed the recording of his hadeeth. Here are some examples:
1. Al-Daarimi and Abu Dawood in their Sunans (books) recorded that Abdullah ibn Amr ibn al-As stated that they used to record everything they heard from the Prophet. They were warned against doing so as, it was argued, the Prophet was a human being who may be angry at times and pleased at others. Abdullah stopped writing his hadeeth until they could ask the Prophet about this issue. The Messenger of Allah told him:
"Write [my hadeeth], by the One in whose hand is my soul, nothing comes out [the Prophet's mouth] except the truth."
That is, whether he was angry or pleased what he spoke was always the truth.
2. Al-Bukhari, in his Sahih (book), recorded that Abu Hurairah said, "One can find none of the Companions of the Messenger of Allah relating more hadeeth than I, except Abdullah ibn Amr because he used to record the hadeeth while I did not do so."
3. Al-Bukhari recorded that a person from Yemen came to the Prophet on the day of the Conquest of Mecca and asked him if he could get the Prophet's speech recorded, and the Prophet approved and told someone:
"Write it for the father of so and so."
4. Anas narrated the statement, "Secure knowledge by writing it." This hadeeth has been related by a number of authorities but mostly with weak chains. There is a dispute concerning whether or not it is actually a statement of the Prophet or of some Companion. However, according to al-Albani, the hadeeth, as recorded by al-Haakim and others, is authentic.
There is no question, therefore, that the recording of hadeeth began during the lifetime of the Messenger of Allah himself. This practice of writing hadeeth continued after the death of the Messenger of Allah. Al-Azami, in his work Studies in Early Hadeeth Literature, has listed and discussed some fifty Companions of the Prophet who had recorded hadeeth. Note the following:
Abdullah B. Abbas (3 B.H.-68 A.H.). He was so eager for knowledge that he would ask as many as 30 Companions about a single incident. It seems he wrote what he heard and sometimes even employed his slaves for this purpose. The following derived hadeeth from him in written form: Ali b. Abdullah ibn Abbas, Amr b. Dinar, Al-Hakam b. Miqsam, Ibn Abu Mulaikah, Ikrimah. Kuraib, Mujahid, Najdah. Said b. Jubair.
Abdullah B. Umar B. al-Khattab (10 B.H.-74 A.H.). He transmitted a large number of ahadeeth, and was so strict in relating them that he did not allow the order of a word to be changed even though it would not have altered the meaning. He had books. One Kitab [book] which belonged to Umar, and was in his possession, was read to him by Nafi several times. The following derived hadeeth from him in written form: Jamil b. Zaid al-Tai. Nafi client of ibn Umar, Said b. Jubair, Abd al-Aziz b. Marwan, Abd al-Malik b. Marwan, Ubaidullah b. Umar, Umar b. Ubaidullah .
Al-Azami also compiled a list, discussing each personality individually, of forty-nine people of "the first century successors" who recorded hadeeth. Al-Azami goes on to list eighty-seven of "the scholars covering the late first and early second centuries" who recorded hadeeth. Then he lists "from the early second century scholars" 251 people who collected and recorded hadeeth. Thus al-Azami has produced a list of 437 scholars who had recorded hadeeth and all of them lived and died before the year 250 A. H. Many of them are from before the time of Umar ibn Abdul Azeez, who has been wrongly credited with having been the first person to ask for the collection of hadeeth. The story of Umar ibn Abdul Azeez has actually been misunderstood and it does not mean that no one collected hadeeth before him.
To quote al-Azami, "Recent research has proved that almost all of the hadeeth of the Prophet was [sic] written down in the life of the companions, which stretched to the end of the first century." This last statement is partially based on al-Azami's own research in which he has mentioned many Companions and Followers who possessed written hadeeth. Elsewhere, he himself writes,
I have established in my doctoral thesis Studies in Early Hadeeth Literature that even in the first century of the Hijra many hundreds of booklets of hadeeth were in circulation. If we add another hundred years, it would be difficult to enumerate the quantity of booklets and books which were in circulation. Even by the most conservative estimate they were many thousands.
The Importance and History of the Isnad
Another important tool used in the preservation of hadeeth was the Isnad system that was developed uniquely by the Muslim nation. The Isnad system is where one states his sources of information, in turn tracing that narrative all the way back to the Prophet, may Allah bless him.
The importance of the Isnad has been eloquently stated by Abdullah ibn al-Mubaarak who said, "The Isnad is part of the religion. If it were not for the Isnadanyone would say whatever he wishes to say." Indeed, the Isnad has been essential in separating the authentic from the weak hadeeth and in identifying the fabricated hadeeth. Even today, no one can dare narrate a hadeeth without possibly being asked to provide the source of that hadeeth. Ibn al-Mubaarak continued and said, "If you ask the person where he got the hadeeth from he will [be forced to] become silent." The Isnad acted and acts as a type of guarantee or safeguard for the authenticity of the hadeeth. The early scholars of hadeeth would not even consider a hadeeth if it had no known Isnad to it.
Concerning the importance of the Isnad, Sufyaan al-Thauri (d. 161) said, "The Isnad is the sword of the believer. Without his sword with him with what will he fight?" By the use of the Isnad, the Muslim scholars were able to eradicate (or "fight") the innovations that some people tried to bring into Islam. Muhammad ibn Seereen (d. 110), Anas ibn Seereen, Al-Dhahaak and Uqba ibn Naafi have all been reported to have said, "This knowledge [of hadeeth] is the religion, therefore, look to see from whom you are taking your religion." Since the Sunnah forms an essential part of Islam, accepting hadeeth from a certain person is similar to taking one's religion from him. Hence, one must be careful only to take his religion from people who are trustworthy and who can trace what they have said back to the Prophet and this can only be done through the use of the Isnad.
This system was even more of a safeguard than today's system of publication and copyrighting. Hamidullah wrote:
"Modern scholars quote, in learned works, the sources of important statements of facts. But even in the most carefully documented works, there are two drawbacks:
(a) In case of published works, there is little or no possibility of verifying whether there are any misprints or other inaccuracies¾ this would not happen if one were to depend on a work only after hearing [it] from the author himself, or obtaining a copy certified by the author, or¾ in case of old works¾ by those who have had the opportunity of hearing it from the author, or his authorized transmitter.
(b) One is contented now-a-days with one's immediate source, without much caring to trace the preceding sources of that source, and mounting in seriatim up to the eye-witness of the event. In Hadeeth works the case has been different."
In conclusion, one may state that the Isnad is an essential component of every hadeeth as without it there is no way for anyone to verify the authenticity of the narration. Abdullah ibn al-Mubaarak certainly spoke the truth when he said that without the Isnad anyone is free to say whatever he wishes to say and claim that it is part of the religion of Islam.The importance of the Isnad is, in fact, very obvious and very few have ever questioned its importance. More important, therefore, is a discussion of when the Isnad began to be used for if it were not until a long time after the death of the Prophet, it would, in fact, be useless.
In his Ph.D. dissertation, Umar Fullaatah has discussed the history of the Isnad in great detail. Due to space limitations, it is not possible to present his discussion in detail. However, he has made the following important conclusions:
Concerning when the Isnad was first used with respect to the transmitting of hadeeth, he states that, by default, the Companions used to use Isnads but since there was usually no intermediary between them and the Messenger of Allah it was not obvious that they were relating through the Isnad. The Companions would either narrate the hadeeth in a manner that made it clear that they heard it directly from the Prophet, or in a manner that made it clear that they may not have heard that particular hadeeth directly from the Prophet. Fullaatah states that the vast majority of the hadeeth of the Companions were those hadeeth that they had heard directly from the Messenger of Allah. Therefore, the Isnad was first used during the time of the Companions although, it may be said, that it was hardly noticeable.
The Preservation of Isnad
Concerning when the narrators were forced by the listeners to mention their Isnads, Fullaatah states that Abu Bakr, the first caliph who died only two years after the Prophet, was the first to make the narrator prove the authenticity of his narration as he sometimes would not accept a hadeeth unless the person presented a witness for his hadeeth. Umar also followed the same pattern. By doing so they made it clear if the person heard the hadeeth directly from the Messenger of Allah or through some intermediary source. Their goal was to confirm the correctness of the narration although they were, at the same time, inadvertently making the narrator state the Isnad for his hadeeth. Therefore, it was during their time (right after the death of the Prophet) that narrators were first being forced to state their Isnads. Ali, the fourth caliph and the caliph during the fitnah (affliction), would sometimes take an oath from the person in which the person would swear that he heard the hadeeth directly from the Prophet. Obviously, then, after the fitnah, the same process of requiring the narrator to state his sources continued.
Concerning when the narrator himself began to insist on mentioning the Isnad of each hadeeth, Fullaatah states that the need for the Isnad really became apparent after weak narrators and immoral people began to relate hadeeth. During that time, the narrator himself made sure that he would mention the Isnadof the hadeeth he narrated. Al-Amash used to narrate hadeeth and then say, "Here is the head of the matter," and then he would mention the Isnad. Al-Waleed ibn Muslim of al-Shaam stated, "One day al-Zuhri said, 'What is wrong [with you people] that I see you narrating hadeeth without the critical or important part?' After that day our companions [that is, the people of al-Sham (Northern Arabia)] made sure to mention the Isnad." The scholars would blame their students for listening to hadeeth from teachers who would mention the hadeeth without the Isnad In fact they would reject any hadeeth which did not have an Isnad with it. Bahz ibn Asad said, "Do not accept a hadeeth from someone who does not say, 'He narrated to us..," that is, without an Isnad. The Muslims even began to insist on the use of the Isnad for people of disciplines other than hadeeth, for example, history, tafseer (explanation of the Qur'an), poetry and so on.
Therefore, after discussing the question in detail, Fullaatah could soundly conclude the following:
1. The Isnad was first used during the time of the Companions.
2. Abu Bakr was the first to force narrators to mention the source for their hadeeth.
3. The narrator himself insisted on mentioning the Isnad of each hadeeth on the heels of (1) and (2) above.
In conclusion, there was never any time that hadeeth narrations were completely void of mentioning the Isnad. During the time of the Companions the use of the Isnad was not so obvious as there was (usually) no intermediate narrator between the person mentioning the hadeeth and the Prophet. (The period of the Companions "officially" ended in 110 A. H. with the death of the last Companion.) Abu Bakr and Umar were scrupulous in checking the authenticity of hadeeth. Later scholars like al-Shabi and al-Zuhri appeared and they made the Muslims realize the importance of mentioning the Isnad with the hadeeth. This was especially manifest after major confrontations (such as the death of Uthmaan) which made the people realize that the hadeeth narrations were their religion and, therefore, they should look carefully at whom they were taking their religion from. After the early years, the Isnad and its proper use became standardized and its knowledge became an independent branch of hadeeth. This continued until the major collections of hadeeth were compiled in the third century.
In reality, Allah blessed the nation of Muhammad with a unique way of preserving its original teachings: the Isnad. Muhammad ibn Haatim ibn al-Mudhaffar wrote:
"Verily Allah has honored and distinguished this nation and raised it above others by the use of the Isnad. None of the earlier or present nations have unbroken Isnads. They have [ancient] pages in their possession but their books have been mixed with their historical reports and they are not able to distinguish between what was originally revealed as the Torah or the Gospel and what has been added later of reports that have been taken from untrustworthy [or, most likely, unknown] narrators."
Early Hadeeth Criticism and Evaluation of Narrators
Another important aspect in the preservation of hadeeths was the early development of hadeeth criticism and evaluation of narrators. Even during the lifetime of the Messenger of Allah, the Companions would often go to him to confirm some report that they had heard related on his authority. Professor Azami, referring to examples in the hadeeth collections of Ahmad, al‑Bukhari, Muslim and al‑Nasaai, writes:
"If criticism is the effort to distinguish between what is right and what is wrong, then we can say that it began in the life of the Prophet. But at this stage, it meant no more than going to the Prophet and verifying something he was reported to have said.
"We find this sort of investigation or verification was carried [sic] out by Ali, Ubai ibn Kaab, Abdullah ibn Amr, Umar, Zainab wife of ibn Masud, and others. In the light of these events, it can be claimed that the investigation of hadeeth or, in other words, criticism of hadeeth began in a rudimentary form during the life of the Prophet."
Obviously this practice of confirming reports directly with the Messenger of Allah had to cease with the death of the Prophet, may Allah praise him. At that time the Companions, led by notables such as Abu Bakr, Umar, Ali, ibn Umar and others, used to confirm hadeeth with each other. Umar, for example, was strict in safeguarding the proper dissemination of hadeeth. In Sahih Muslim one can find the example of Abu Moosa al‑Ashari. Umar threatened to have him punished if he did not present a witness for a hadeeth that he had narrated to Umar. Commenting on this hadeeth, Abdul Hamid Siddiqi stated that Umar did not doubt Abu Moosa but he only meant to keep a strict supervision over the transmission of hadeeth.
Many examples of this kind may be given. Abu Hurairah, Aishah, Umar and ibn Umar would verify hadeeth. Sometimes they would verify the hadeeth by "cross‑reference" (like Umar and Abu Moosa above) and at other times they used what could be termed "time‑series" checking. Imam Muslim records that Aishah heard a certain hadeeth narrated from Abdullah ibn Amr. A year later she had her servant go to Abdullah ibn Amr to hear the hadeeth again from him to make sure that he had narrated it exactly as he had heard it from the Prophet and that he had not made any mistakes or additions in its narration.
This investigation of narrators led to the development of the most fascinating and unique science of al-jarh wa al-tadeel, wherein the lives, academic qualities and moral qualities of literally thousands of narrators are discussed in detail. Every narrator must meet both moral and academic qualifications for his hadeeth to be accepted. One, without the other, is simply not sufficient. An individual may have a great memory or be able to record material very accurately but if he is not considered a completely honest and trustworthy person, his narrations of hadeeth, the most important information an individual can pass on, will not be accepted. Similarly, a person may be a very pious and honest individual but if he does not posses the literary or academic qualities to be able to pass on information accurately and correctly, his narrations also cannot be relied on.
Thus, the scholars developed many means by which to test the proficiency and accuracy of the narrators of hadeeth. Azami states that there are four basic ways to check the proficiency of a narrator. He has given examples of each type. The four are:
(1) Comparison between the hadeeth of different students of the same scholar. An example is that of Yahya ibn Maeen who read the books of Hammad ibn Salama to seventeen of Hammad's students. He said that by doing so he would be able to spot the mistakes that Hammad made (by comparing them to what other scholars had narrated) and the mistakes that each individual student made (by comparing them with the other students of Hammad).
(2) Comparison between the statements of a single scholar at different times. Mention was made earlier of the Hadeeth of Aisha in which she had Abdullah ibn Amr ibn al‑As asked about a hadeeth that he had narrated a year earlier. When she found that he had not made any change in the hadeeth she knew that he had memorized it exactly as he heard it from the Prophet.
(3) Comparison between oral recitation and written documents. Azami gave the following example:
Abdur Rahman b. Umar transmitted a hadeeth through Abu Huraira concerning Dhuhr prayer [the noon prayer], which may be delayed in summer [sic] from its early time. Abu Zurah said that it is incorrect. This hadeeth was transmitted on the authority of Abu Said. Abdur Rahman b. Umar took it very seriously and did not forget it. When he returned to his town, he checked in his book and found himself mistaken. Then he wrote to Abu Zurah, acknowledging his mistake, asking him to take trouble [sic] and inform such and such person and other people who had asked about it from his students, and to tell them about his mistake, and, he said Allah would give him the reward, for shame is much better than Hell.
(4) Comparison between the hadeeth and the text of the Qur'an. This practice started with the Companions. The Qur'an was the first test that the hadeeth would have to pass. The Companions would not accept any hadeeth that contradicted the Qur'an; instead they would conclude that the Companion must have been mistaken or had misunderstood what the Prophet had narrated. They knew that the Qur'an and Sunnah were essentially one revelation and it was not possible for one to contradict the other.
Azami only mentions the above four methods of checking the proficiency of a narrator but there were others. The following were quite common: comparing what one narrator related to what others narrated (that is, not students of the same teacher), comparing one Sunnah with another and comparing the text of the hadeeth with well‑known historical events.
Traveling for the Purpose of Seeking Hadeeth
Another unique phenomenon that appeared and assisted in the preservation of the Sunnah was the traveling in search of hadeeth, in order to check the sources and gather more hadeeth together. Among all of the different religious communities of the world it has been only the Islamic nation that has been blessed with two particular characteristics that have saved it from losing its original and pure teachings. These two unique characteristics are the use of the Isnad, which has just been discussed, and the journeys undertaken in search of hadeeth, that shall presently be discussed. The great desire for religious knowledge among the Muslims led individuals to travel, on their own, for months at a time simply to collect or confirm just one saying of the Prophet, may the blessing and mercy of Allah be upon him. It was this devotion to hadeeth and willingness to sacrifice any aspect of this worldly life that greatly helped in the complete preservation of the hadeeth of the Prophet. M. Zubayr Siddiqi has written:
All these various generations of "Traditionists" displayed marvelous activity in the pursuit of hadeeth. Their love for the subject had been profound. Their enthusiasm for it knew no bounds. Their capacity to suffer for the sake of it had no limit. The rich among them sacrificed riches at it's alter; and the poor among them devoted their lives to it in spite of their poverty.
Why was this desire for knowledge so great among these early Muslims? No one can answer this question completely but there must have been many reasons for this strong desire. These reasons must have included the following:
(a) The knowledge of hadeeth was known by these pious souls to lead them to the practice of the Prophet and, furthermore, they knew that by following his footsteps they would become closer to Allah.
(b) The Qur'an and the Prophet both stressed the virtues and importance of attaining knowledge. Allah says:
".Say: Are those who are knowledgeable equal to those who are not knowledgeable?..." (Qur'an 39:9)
".The knowledgeable among His bondsmen fear Allah alone." (Qur'an 35:28)
Among the Prophet's many statements on this topic are:
"Whoever goes out along a path in search of knowledge, Allah makes a path to Paradise easy for him."  (Saheeh Muslim)
The Prophet also said,
"When the son of Adam dies all of his good deeds come to an end except three: a perpetual charity, beneficial knowledge [he left behind from which people gain some benefit] and a pious child who supplicates for him." (Saheeh Muslim)
The early scholars recognized the importance of attaining knowledge and they also recognized that no knowledge is better than knowledge about the Creator. Therefore, they did their best to learn the teachings of His Prophet.
Examples from the early years will give a clearer picture of these journeys in search of hadeeth. In reality, however, traveling in search of hadeeth can be said to have begun during the time of the Prophet himself. That is, even at that time, people would come from outside of Madinah to ask the Prophet about specific matters. In some cases, they would come to the Prophet to verify what has been reported by the Prophet's representatives. In al-Bukhari andMuslim it can be seen that the other Companions looked forward to such an event. This was because, as Anas stated, they were prohibited from asking the Prophet too many questions, so they would look forward to the coming of an intelligent Bedouin who traveled to come to the Prophet to ask him specific questions.
The following examples are of Companions who traveled in order to verify hadeeth that they themselves heard from the Prophet.
Imam al-Bukhari recorded in his Sahih that Jaabir ibn Abdullah traveled for one month to get a single hadeeth from Abdullah ibn Unais. In a version recorded by al-Tabaraani, it states that Jabir said, "I used to hear a hadeeth on the authority of the Prophet about retribution and the one who narrated that hadeeth [directly from the Prophet] was in Egypt, so I bought a camel and traveled to Egypt..." 
The Companion Abu Ayyoob traveled all the way to Egypt to ask Uqba ibn Amr about one hadeeth. He told Uqba that only he and Uqba were left who had heard that particular hadeeth directly from the Prophet. After hearing the hadeeth his business was completed in Egypt and he returned to Madinah.
One of the Companions traveled to visit Fadhala ibn Ubaid and told him that he came not to visit him but only to ask him about a hadeeth that they had both heard from the Prophet and the Companion was hoping that Fadhala had the complete wording of the hadeeth.
From the stories of the Companions one can conclude that they traveled in search of hadeeth for basically two reasons:
(a) To hear a hadeeth from a fellow Companion concerning which they did not have the honor of hearing it themselves directly from the Prophet, thereby adding to their knowledge of hadeeth.
(b) To confirm the wording and/or meaning of a hadeeth that they and other Companions had heard directly from the Messenger of Allah. Thus even the Companions were constantly checking, rechecking and safeguarding the purity of the hadeeth that they narrated.
In the era of the students of the Companions (termed 'Followers'), the desire and willingness to travel in order only to hear or confirm a hadeeth of the Prophet did not diminish. Madinah, having been the home of the Prophet for many years, the home of the Sunnah and the city where many of the Companions resided after the Prophet's death, was probably the main center of attraction, but, in fact, any place where it was known a particular hadeeth could be heard would attract "travelers."
Many examples could be given. Al-Khateeb al-Baghdadi has written an entire work on the subject of traveling in search of hadeeth. His work is entitled Al-Rihla fi Talab al-Hadeeth ("Travels in Search of Hadeeth"). What makes this work even more interesting is that it is not simply concerned with scholars traveling to learn hadeeth. This was done by almost every scholar in the history of Islam. Indeed, if a scholar did not travel that was usually pointed out as something strange, as the norm was to travel. However, this book, as pointed out by the editor of the work Noor al-Deen Itr, is about travels in search of just one hadeeth and not hadeeth in general..!
The above has been a very brief description of some of the important means by which Allah has preserved the ever-important Sunnah of the Prophet Muhammad, may the blessing and mercy of Allah be upon him. One of the important aspects to note is that these safeguards started going into effect virtually during the time of the Prophet himself. There was no time lag, leaving the door open to a massive loss of information or to distortion.
In the following statement, M. Z. Siddiqi has done an excellent job of summing up the protection of the sunnah in the early years:
The Hadeeth in the sense of the reports of the sayings and doings of Muhammad has been a subject of keen pursuit and constant study by the Muslims throughout the Muslim world since the very beginning of the history of Islam up to the present times. During the life-time of Muhammad many of the companions tried to learn by heart whatever he said, and observed keenly whatever he did; and they reported these things to one another. Some of them wrote down what he said in Saheefahs (scrolls) which were later on read by them to their students, and which were preserved in their families and also by the Followers. After the death of Muhammad, when his companions spread in various countries, some of them as well as their followers undertook long arduous journeys, courted poverty and penury in order to collect them together. Their remarkable activity with regard to the preservation and propagation of hadeeth is unique in the literary history of the world. [And the excellence of their sciences remains] unparalleled in the literary history of the world even to-day.
It was these processes that ultimately culminated in the fine-tuned sciences of hadeeth and the detail grading of the reports traced back to the Prophet. In general, the scholars would not accept a report as an authentic hadeeth unless that report can be verified with a complete chain made up of only sound and trustworthy narrators all the way back to the Prophet. Anything short of that would be rejected as a weak hadeeth.
The more one goes on to study the sciences of hadeeth, the more he/she will feel comfortable with the feeling that the teachings of the Prophet Muhammad has been minutely preserved, just as Allah had promised in the Qur'an. When the scholars of hadeeth - who are the specialists in that field and who have spent their lifetime in mastering that discipline - agree upon the authenticity of a hadeeth, there should be no need for debate or question. The only thing left to do is to believe in it and do one's best to apply the meaning of that hadeeth in one's life.
Comparison with Other Scriptures
When referring to the hadeeth of the Prophet, it is commonplace for some Westerners to use the word "tradition." This immediately brings forth the impression of a very haphazard and unscholarly report. The reality, as alluded to above, is completely different. The use, therefore, of this word "tradition" may be nothing more than a smokescreen to give the impression that the hadeeth were not preserved. Another common description that appears is a reference to the preservation of the hadeeth as being similar to that of the Gospels.
This is also a rather clever phrase that definitely has negative connotations to it for many. In fact, many converts have studied the Gospels and know how unreliable they are - this being one of the reasons why they began to search for a religion other than Christianity. Therefore, such a statement will quickly shake their faith in hadeeth.
The stark reality is that no honest comparison can be made between the minute and scientific preservation of the hadeeth of the Prophet and the preservation of the earlier scriptures. A few brief descriptions of the preservation - or lack thereof - of the earlier scriptures should suffice to contrast them with the preservation of the hadeeth.
After a lengthy discussion of the history of the Torah, Dirks concludes:
The received Torah is not a single, unitary document. It is a cut-and-paste compilation. with additional layering. While Moses, the person who received the original revelation, which the Torah is supposed to represent, lived no later than the 13th century BCE, and probably lived in the 15th century BCE, the received Torah dates to a much later epoch. The oldest identifiable substrata of the received Torah, i.e., J, can be dated no earlier than the 10th century BCE. Further, these different substrata were not combined into a received Torah until approximately 400 BCE, which would be approximately 1,000 years after the life of Moses. Still further, the received Torah was never totally standardized, with at least four different texts existing in the first century CE, which was approximately 1,500 years after the life of Moses. Additionally, if one adopts the Masoretic text as the most "official" text of the received Torah, then the oldest existing manuscript dates to circa 895 CE, which is about 2,300 years after the life of Moses. In short, although the received Torah may well contain some portions of the original Torah, the provenance of the received Torah is broken, largely unknown, and can in no way be traced to Moses.
Although Jesus came many centuries after Moses, the revelation that he received did not fare much better. A group of Christians scholars known as the Fellows of the Jesus Seminar tried to determine which of the sayings attributed to Jesus can actually be considered authentic. They stated, "Eighty-two percent of the words ascribed to Jesus in the gospels were not actually spoken by him."  In describing the history of the gospels, they wrote, "The stark truth is that the history of the Greek gospels, from their creation in the first century until the discovery of the first copies of them at the beginning of the third, remains largely unknown and therefore unmapped territory."  Bart Ehrman's work The Orthodox Corruption of Scripture has identified how the scripture has been changed over time. He states his thesis, which he proves in detail, at the outset, "My thesis can be stated simply: scribes occasionally altered the words of their sacred texts to make them more patently orthodox and to prevent their misuse by Christians who espoused aberrant views." That is something like putting the cart before the horse: The beliefs should be based on the transmitted texts; not that the texts should be altered to fit the beliefs.
A Final Note about the Qur'an
The nature of the Qur'an is very different from that of the statements and actions of the Prophet. Obviously, the statements and actions are very large in number while the Qur'an is very limited in size. The Qur'an, which is not a large book at all, was preserved in memory as well as written form from the time of the Prophet Muhammad himself. Many of the Companions of the Prophet had memorized the entire Qur'an and, fearing what had happened to earlier religious communities, they took the necessary steps to protect it from any form of adulteration. Soon after the death of the Prophet, the Qur'an was all compiled together and shortly afterwards official copies were sent to the distant lands to ensure that the text was pure. To this day, one can travel to any part of the world and pick up a copy Qur'an and find that it is the same throughout the world. The task of preserving the Qur'an cannot actually compare to the task of preserving the bulk of the Sunnah. Hence, it is no surprise, given the attitude of the Muslims of that time, that the Qur'an was minutely preserved.
1) This author has discussed in great detail the position and role of the Sunnah in Islam in his The Authority and Importance of the Sunnah (Denver, CO: Al-Basheer Company, 2000).
2) The Qur'an itself refers to the distortion of the earlier books by the previous peoples as well as their attempts to conceal some of the revelation. See, for example, Qur'an 5:14-15 and 4:46.
3) See Abdul Muhsin al-Abbaad, Diraasat Hadeeth Nadhara Allahu imraan Sama Muqaalati...: Riwaayah wa Diraayah (no publication information given), passim.
4) Cf., Sulaimaan al-Tabaraani, Turuq Hadeeth Man Kadhaba Alayya Mutamadan (Beirut: al-Maktab al-Islaami, 1990), passim.
5) One of the most noteworthy commentators of Saheeh Al-Bukhari - IslamReligion.com
6) Ahmad ibn Hajar, Fath al-Baari Sharh Saheeh al-Bukhaari (Makkah: Maktabah Daar al-Baaz, 1989), vol. 1, p. 201.
7) This narration was recorded by al-Daarimi. According to Abdul Rahmaan al-Birr, its chain is sahih. Cf., Abdul Rahmaan al-Birr, Manaahij wa Adaab al-Sahaabah fi al-Taallum wa al-Taleem (Al-Mansoorah, Egypt: Daar al-Yaqeen, 1999), p. 183.
8) According to al-Albaani, this hadeeth is sahih. See Muhammad Naasir al-Deen al-Albaani, Saheeh Sunan Abi Dawood (Riyadh: Maktab al-Tarbiyyah al-Arabi li-Duwal al-Khaleej, 1989), vol. 2, p. 695.
9) Ibn Hajar, commenting on this hadeeth, explained how Abu Huraira could have narrated so many more hadeeth than Abdullah ibn Amr. See ibn Hajar,Fath, vol. 1, pp. 206-8. One aspect that he neglected to mention is Abu Hurairah' dying some sixteen years after Abdullah ibn Amr.
10) Al-Albani, Saheeh al-Jaami al-Sagheer, vol. 2, p. 816.
11) Muhammad Mustafa al-Azami, Studies in Early Hadeeth Literature (Indianapolis, IN: American Trust Publications, 1978), pp. 34-60.
12) Azami, Studies in Early Hadeeth, pp. 40-42. In Azami's work, "b." stands for ibn or "son of."
13) Azami, Studies in Early Hadeeth, pp. 45-46.
14) Azami, Early Hadeeth, pp. 60-74.
15) Ibid., pp. 74-106.
16) Ibid., pp. 106-182.
17) The story, as recorded by al-Bukhari, is that Umar (61-101) wrote to Abu Bakr ibn Muhammad (d. 100) saying, "Look for the knowledge of hadith and get it written, as I am afraid that religious knowledge will vanish and the religious learned men will pass away. Do not accept anything save the hadith of the Prophet." He also sent letters to Saad ibn Ibraaheem and al-Zuhri asking them to do the same. It has been incorrectly stated by some, for example, M. Z. Siddiqi, that it was this request of Umar' that led to the beginning of the collections of hadith.
18) Al-Azami, Methodology, p. 30.
19) Ibid., p. 64.
20) Quoted by Imam Muslim in the introduction to his Sahih in the chapter entitled, "Expounding on the point that the Isnad is part of the religion."
21) Quoted in Umar ibn Hasan Uthmaan al-Fullaatah, al-Widha fi al-Hadeeth (Damascus: Maktabah al-Ghazzaali, 1981), vol. 2, p. 10.
22) Muhammad Hamidullah, Sahifah Hammam ibn Munabbih (Paris: Centre Culturel Islamique, 1979), p. 83.
23) One is reminded of the case of Paul and the origins of many Christian beliefs. Paul, of course, never met Jesus (peace be upon him). He could not trace his teachings back to Jesus (peace be upon him) and, in fact, he met opposition from many of Jesus' own companions who knew what Jesus (peace be upon him) had said. Unfortunately, the historical authenticity and tracing of claims back to the original teacher, Jesus, is something that did not truly develop in Christian thought. Hence, their religion became very distorted and distant from the true teachings of Jesus (peace be upon him).
24) Fullaatah, vol. 2, pp. 20-22.
25) Quoted by Fullaatah, vol. 2, p. 28.
26) Ibid., vol. 2, pp. 28-29. See the stories of al-Zuhri, Abdullah ibn al-Mubaarak and Sufyaan al-Thauri on those pages.
27) Fullaatah, vol. 2, p. 30.
28) In fact, the tradition of relating hadeeth by their Isnads continued until the fifth century. After that time books were passed on, mostly by ijaaza(permission given to others to narrate one's books or hadeeth), although there are still some scholars today who can narrate hadeeth with a complete chain from themselves back to the Prophet. Cf., Khaldoon al-Ahdab, Asbaab Ikhtilaaf al-Muhadeetheen (Jeddah: al-Dar al-Saudiya, 1985), vol. 2, p. 707.
29) Quoted in Abdul Wahaab Abdul Lateef, Al-Mukhtasar fi Ilm Rijaal al-Athar (Dar al-Kutub al-Hadeethiya, no date), p. 18.
30) Mustafa Muhammad Azami, Studies in Hadeeth Methodology and Literature (Indianapolis, IN: American Trust Publications, 1977), p. 48.
31) Abdul Hamid Siddiqui, trans. and commentator, Sahih Muslim (Lahore, Pakistan: Sh. Muhammad Ashraf, 1972), vol. 3, pp. 1175‑6.
32) Ibid., vol. 4, p. 1405.
33) Azami, Methodology, pp. 52‑58.
34) Azami, Methodology, p. 56.
35) M. Z. Siddiqi, Hadeeth Literature: Its Origin, Development, Special Features and Criticism (Calcutta: Calcutta University Press, 1961), p. 48.
36) Saheeh Muslim.
37) Saheeh Muslim.
38) For more examples see Akram Dhiyaa Al-Umari, Buhooth fi Tareekh al-Sunnah al-Musharrifah (Beirut: Muassasah al-Risaalah, 1975), pp. 203f.
39) Ibn Hajar says that this version has a good chain. Cf., ibn Hajar, Fath al-Baari, vol. 1, p. 174.
40) This incident was recorded by Abu Dawood.
41) See Noor al-Deen It's introduction to al-Khateeb al-Baghdaadi, al-Rihlah fi Talab al-Hadeeth (Beirut: Daar al-Kutub al-Ilmiyyah, 1975), p. 10.
42) M. Z. Siddiqi, pp. 4-5.
43) Jerald F. Dirks, The Cross & the Crescent (Beltsville, MD: Amana Publications, 2001), p. 53. Other important discussions of the authenticity of the Old Testament may also be found in Maurice Bucaille, The Bible, the Qur'an and Science (Indianapolis, IN: American Trust Publications, 1978), pp. 1-43; M. M. Al-Azami, pp. 211-263.
44) Robert W. Funk, Roy W. Hoover and the Jesus Seminar, The Five Gospels: What did Jesus Really Say? (New York: MacMillan Publishing Company, 1993), p. 5.
45) Funk, et al., p. 9.
46) Bart D. Ehrman, The Orthodox Corruption of Scripture: The Effect of Early Christological Controversies on the Text of the New Testament(New York: Oxford University Press, 1993), p. xi.