Introduction to Hadith and Sunnah: The second most trusted sources for Islam. "Muhammad lived in the full light of history"- French Scholar, Ernest Renan
"An extraordinary aspect of Muhammad's life is that he lived in the full light of history. There are detailed accounts of his life avalible to us. No comparable religious figure's life and times have been so well recorded as Muhammad." - Muqtedar Khan of the Center for the Study of Islam and Democracy.
Why the Hadith
The hadith are sayings or actions of Prophet Muhammad. After the Quran, the hadith are the most trusted sources for Prophet Muhammad's life. The Hadith are based on Isnad part of a chain of people who have passed on the report (insad). Contary to what Christian polemics, Oreintalists and Western Critics of Islam have maintained, the isnad (chain of transmission) was first used by the companions of Prophet Muhamamd to verify a report about the Prophet.
The concept of verifying where a report came from initiated during the Caliphate of Abu Bakr and was common during Umar's caliphate as well.
In his Ph.D. dissertation, Umar Fullaatah after discussing the question of the history of Isnaad in detail confidently concluded 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. 
Some examples would suffice to prove the point that Abu Bakr and Umar found it important to verify the source of the hadith being narrated:
'Abd Allah bin Shaqiq said: Ibn 'Abbas one day addressed us after al-'asr till the sun disappeared and the stars appeared, and (as the time for maghrib passed) the people began to say: Prayer, prayer! A person from Banu Tamim arrived and without slackening or stopping (continued saying): Prayer, prayer! Ibn 'Abbas said: May you be deprived of your mother, do you teach me the Sunnah? And then he said: I saw the Messenger of God combining the noon and afternoon prayers and the sunset and night prayers. 'Abd Allah bin Shaqiq said: Some doubt was created in my mind about it. So I came to Abu Hurayrah and asked him and he testified his assertion. (Muslim Book 004, Number 1523)
Narrated Abu Said Al-Khudri: While I was present in one of the gatherings of the Ansar, Abu Musa came as if he was scared, and said, "I asked permission to enter upon 'Umar three times, but I was not given the permission, so I returned." (When 'Umar came to know about it) he said to Abu Musa, "Why did you not enter?'. Abu Musa replied, "I asked permission three times, and I was not given it, so I returned, for Allah's Apostle said, "If anyone of you asks the permission to enter thrice, and the permission is not given, then he should return.' " 'Umar said, "By Allah! We will ask Abu Musa to bring witnesses for it." (Abu Musa went to a gathering of the Ansar and said). "Did anyone of you hear this from the Prophet ?" Ubai bin Ka'b said, "By Allah, none will go with you but the youngest of the people (as a witness)." (Abu Said) was the youngest of them, so I went with Abu Musa and informed 'Umar that the Prophet had said so. (Bukhari Volume 8, Book 74, Number 262)
It is clear that 'Umar did not consider the report of Abu Musa to be binding despite the fact that he already considered him to be a trusthworthy companion of the Prophet (peace be upon him). Here we see that Abu Bakr insisted that another witness verify what was being attributed to the Prophet (peace be upon him).
Thus, it is clear that the companions of the Prophet (peace be upon him) found it important to verify where the hadith were coming from. This is the whole logic and wisdom of isnaad. Thus, it is fair to say that the isnaad started with the companions.
Moving on to some of the earliest classical scholars:
Moving on to some of the earliest classical scholars:
Abdullah ibn al-Mubaarak the well known Hanafi scholar (born in 118-181 A.H.) was a contemporary of Ibn Ishaq and he said:
"The Isnad is part of the religion. If it were not for the Isnad anyone would say whatever he wishes to say." (Imam Muslim in the introduction to his Sahih in the chapter entitled, "Expounding on the point that the Isnad is part of the religion.")
Concerning the importance of the Isnad, Sufyaan al-Thawri (d. 161 A.H.) another contemporary of Ibn Ishaq 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." 
Dr. Mustafa Al Azami said:
We have just seen that the criticism of Hadith began in the life of the Prophet s.a.w. After his death, Abu Bakr, Umar, Ali, Ibn Umar, Aishah and other Companions took part in it. According to Ibn Hibban, after Umar and Ali came the turn of the Successors Ibn al-Musayyab (d.93 AH.); al-Qasim b. Muhammad b. Abu Bakr (d.106 AH.); Salim b. Abdullah b. Umar (d. 106 AH.); Ali b. Husayn b. Ali (d.93 AH.); Abu Salamah b. Abd al-Rahman (d.94 AH.); Abdullah b. Abdullah b. Utbah; Kharijah b. Zayd b. Thabit (d.100 AH.); Urwah b. Al Zubayr (d.94 AH); Abu Bakr b. Abd al-Rahman b. al-Harith (d.94 AH) and Sulayman b. Yasar.
It is interesting to note that all of these scholars belong to the first century of Hijrah, though a few of them lived in the first decade of the second century. Later on, in the Madinah region, there were three scholars al-Zuhri, Yahya b. Said, and Hisham b. Urwah who learned this science from the above-mentioned scholars. The most famous of these three was al-Zuhri (d. 124 AH.)
In Iraq too the Hadith critics were active in the first century, prominent among them being Said b. Jubayr, al-Sha'bi, Tawus, al-Hasan al-Basri (d. 110 AH.) and Ibn Sirin (d. 110 AH.) 
It’s commonly said by the critics of Islam that the hadith (stories, actions, sayings of Prophet Muhammad) started 200 years after the Prophet’s death. However this is not true. There were many books of hadith which came right after Prophet Muhammad died. There were several hadith books prior to the birth of Bukhari.
Following is a list of 59 books of hadith collections prior to Bukhari:
1. Book of Khalid ibn Ma'dan (d. 104 A.H.)
2. Books of Abu Qilabah (d. 104). He bequeathed his books to his pupil, Ayyub Saktiyan (68-131 A.H.), who paid more than ten dirhams as a fare for them being loaded on a camel.
3. The script of Hammam ibn Munabbih, already referred to.
4. Books of Hasan al-Basri (21-110 A.H.)
5. Books of Muhammad al-Baqir (56-114 A.H.)
6. Books of Makhul from Syria
7. Book of Hakam ibn 'Utaibah
8. Book of Bukair ibn 'Abdullah ibn al-Ashajj (d. 117)
9. Book of Qais ibn Sa'd (d. 117). This book later belonged to Hammad ibn Salamah.
10. Book of Sulaiman al-Yashkuri
11. Al-Abwâb of Sha'bi, already referred to.
12. Books of Ibn Shihâb az-Zuhri
13. Book of Abul-'Aliyah
14. Book of Sa'id ibn Jubair (d. 95)
15. Books of 'Umar ibn 'Abdul Aziz (61-101 A.H.)
16. Books of Mujahid ibn Jabr (d. 103)
17. Book of Raja ibn Hywah (d. 112)
18. Book of Abu Bakr ibn Muhammad ibn 'Amr ibn Haq
19. Book of Bashir ibn Nahik.
20. Book of 'Abdul Malik ibn Juraij (d. 150)
21. Muwatta of Malik ibn Anas (93-179)
22. Muwatta of Ibn Abi Zi'b (80-158)
23. Maghâzi of Muhammad ibn Ishaq (d. 151)
24. Musnad of Rabi' ibn Sabih (d. 160)
25. Book of Sa'id ibn Abi 'Arubah (d. 156)
26. Book of Hammad ibn Salmah (d. 167)
27. Jami' Sufyan ath-Thauri (97-161)
28. Jami' Ma'mar ibn Rashid (95-153)
29. Book of 'Abdur-Rahman al-Awzâ'I (88-157)
30. Kitâb az-Zuhd by 'Abdullâh ibn al-Mubârak (118-181)
31. Book of Hushaim ibn Bashir (104-183)
32. Book of Jarir ibn 'Abdul-Hamid (110-188)
33. Book of 'Abdullâh ibn Wahb (125-197)
34. Book of Yahya ibn Abi Kathîr (d. 129)
35. Book of Muhammad ibn Suqah (d. 135)
36. Tafsîr of Zaid ibn Aslam (d. 136)
37. Book of Musa ibn 'Uqbah (d. 141)
38. Book of Ash'ath ibn 'Abdul-Malik (d. 142)
39. Book of Aqil ibn Khalid (d. 142)
40. Book of Yahya ibn Sa'id Ansari (d. 143)
41. Book of Awf ibn Abi Jamilah (d. 146)
42. Books of Jafar ibn Muhammad al-Sadiq (d. 148)
43. Books of Yunus ibn Yazid (d. 152)
44. Book of 'Abdur-Rahman al-Mas'udi (d. 160)
45. Books of Zaidah ibn Qudamah (d. 161)
46. Books of Ibrahim al-Tahman (d. 163)
47. Books of Abu Hamzah al-Sukri (d. 167)
48. Al-Gharâib by Shu'bah ibn al-Hajjaj (d. 160)
49. Books of 'Abdul-Aziz ibn 'Abdullâh al-Majishun (d. 164)
50. Books of 'Abdullâh ibn 'Abdullâh ibn Abi Uwais (d. 169)
51. Books of Sulaiman ibn Bilal (d. 172)
52. Books of 'Abdullâh ibn Lahi'ah (d. 147)
53. Jami' Sufyan ibn 'Uyainah (d. 198)
54. Kitâb-ul-Âthâr by Imâm Abu Hanîfah (d. 150)
55. Maghâzi of Mu'tamir ibn Sulaiman (d. 187)
56. Musannaf of Waki' ibn Jarrah (d. 196)
57. Musannaf of 'Abdur-Razzâq ibn Hammam (136-221)
58. Musnad of Zaid ibn 'Ali (76-122)
59. Books of Imâm Shâfi'i (150-204)
Dr. Mustafa Al Azami in his excellent acclaimed work Studies in Early Hadith Literature from pages 34 to 60 mentions the names of 50 companions of the Prophet (peace be upon him) who wrote down hadith. Then from pages 60 to 74 he mentions the names of 49 successors from the first Islamic century that wrote down hadith. Then from pages 74 to 106 he mentions the names of 87 scholars that wrote down hadith from the late first and early second centuries. Then from pages 106 to 182 he mentions the names of 251 scholars from the early second century who wrote down hadiths.
This is clear evidence that the writing down and collection of hadith started much earlier than most people think.Now one might ask himself why we don't have most of these first century hadith works.
Dr. Mustafa Al Azami in his other acclaimed work Studies in Hadith Methodology and Literature on page 103 said:
What happened to the earlier Hadith literature? I have mentioned earlier that hundreds and thousands of books of Hadith were in circulation in the first and second century. Only a very small amount of this Hadith literature has survived. It could be said that either what I have described is totally wrong, or these books were in existence at sometime but were lost later. This second hypothesis raises another problem, i.e. of the negligence of the Hadith of the Propeht s.a.w. by Muslim scholars. It is possible that they did not feel any necessity of Hadith literature and so it was destroyed?
As a matter of fact, my position is precise and correct. These books were not destroyed nor did they perish, but were absorbed into the work of later authors. When the encyclopedia type books were produced, scholars did not feel the necessity to keep the early books or booklets, and so, slowly they disappeared. To explain this point I will describe the method of quotations in early days which would prove my point.
So there were many books of hadith in circulation before Bukhari’s collection of hadith. Other examples of first century hadith collections would include The Sahifa Of Hammam bin Munabbih: This is perhaps one of the earliest known hadith collections. According to the book Arabic Literature To The End of Ummayyad Periodt:
“An example is the Sahifah of Hammam bin Munabbih, (d. 110/719), a Yemenite follower and a disciple of companion Abu Hurrayrah, (d. 58/677), from whom Hammam wrote this Sahifah, which comprises 138 hadith and is believed to have been written around the mid-first AH/seventh century.” 
There are six trusted collectors of hadith (stories and sayings of Prophet Muhammad) listed below:
Bukhari (810-870 CE) Muhammad ibn Ismail al-Bukhari, or Bukhari for short. He was a scholar from Bukhara and is considered the most reliable or trustworthy complier of hadith. He collected over 300,000 hadith however only recorded about 2,602 in his collection. Shia Muslims however view Bukhari to be mostly unreliable and believe he fabricated a lot of hadith. Some Western Scholars also have trouble with Bukhari beliving both valid and invalid hadith are in his collection. 
Muslim (818-875 CE) Imam Muslim ibn al-Hajjal or Muslim for short. He, like Bukhari, traveled wide from places to Iraq, Saudi Arabia to Egypt to collect hadith. Out of 300,000 hadith he recorded only about 4000 were written in his collection. Sunni Muslims consider Muslim hadiths to be the second most reliable hadith collection after Bukhari. It should be noted that Muslim never claimed to have collected authentic sayings and actions of Prophet Muhammad. There are some weak hadith in his collection according to his own sayings.
Al-Nasā'ī ( 829-915 CE) Nasai’s hadith collection is regarded as the third most authentic hadith collection. His collection has about 5270 hadith.
Abu Dawod (817-888 CE) Abu Dawod is another collector of the six canonical collections of Hadith. Abu Dawod traveled from Iraq to Egypt to Marv to collect quoatations of hadith. From about 50,000 hadith, he only put 4800 in his collection as authentic. Some Islamic scholars state that some of his hadith are not authentic however he disagreed. This is because some Islamic scholars maintained that he lacked an Insad or a chain of transmitters for his hadith. Abu Dawod has indicated that some of his hadith were unauthentic in his later collections, however most of his hadith are authentic by a majority of Islamic scholars.
Al-Tirmidhi (824-892 CE) Tirmidhi was a scholar on hadith and wrote nine books concerning how to classify hadith and the sciences of hadith. Sunni Muslims regard his collection as the fifth most reliable collection in the six canonical collections of hadith.
Ibn Majah (824-887 CE) Ibn Maja was a scholar of hadith, Islamic history and the Quran. While traveling throughout the Middle East to study Islam, he collected about 4,341 hadiths, of which 3,002 are recorded by the other five canonical hadith collectors; of the 1,339 hadith are accredited to him, while 428 are graded sahih (authentic), while the rest are not considered authentic by others.
Muslim and Hadith scholars, due to the controversy of people making up hadith, made a criteria to determine if a hadith is reliable or not. They came up with the critea of doing so by classifying hadith in these three categories:
Sound (sahih): Almost certainly true
Good (Hasan): Very possibly true.
Weak (da’if): Is not considered true unless it’s confirmed by other sources of hadith.
The hadith scholars would determine the morals and characters of the isnad or the chain of people who told the report. After that they would determine whether or not it is sound, good or weak. 
It should also be noted that Shia Muslims use different hadith books. Since I am a Sunni (orthodox) Muslim and promote only orthodox Islam, I will not
go into Shia Sources here.
 Fullaatah, al-Widha fi al-Hadeeth, vol. 2, p. 30
 Quoted in Umar ibn Hasan Uthmaan al-Fullaatah, al-Widha fi al-Hadeeth (Damascus: Maktabah al-Ghazzaali, 1981), vol. 2, p. 10
 Dr. Mustafa Al Azami, Studies in Hadith Methodology and Literature, page 67
 A. F. L. Beeston, T. M. Johnstone, R. B. Serjeant and G. R. Smith (Ed.), Arabic Literature To The End of Ummayyad Period, 1983, Cambridge University Press, p. 272.
 Clark, Malcolm: Islam for Dummies, Wiley Publishing, Inc. Indianapolis, Indiana 2003 page 124.