After a period many of the ahadith started getting mixed with the saying of the sahaba, the fatawa of the tabieen and those after them. Imam Bukhari found many of the writings had incorporated weak ahadith in them, so he made a firm resolve to compile a saheeh. So he strengthened this resolve upon that which he heard from his teacher, leader of the believers in hadith and fiqh, Ishaq ibn Ibrahim al-Hindhali, known as Ibn Rahawaih. This was the wish of his teacher[1].
Although it is more prominently known as Saheeh al-Bukhari, the actual name of the book as penned by Imam Bukhari is الجامع الصحيح المسند من حديث رسول الله ﷺ وسننه وأيامه. Translated as the abridged collection of authentic narrations with connected chains regarding matters pertaining to the Prophet ﷺ, his practices and his times.
It is mentioned that Imam Bukhari’s saheeh is the most authentic book after the Quran. There are 7275 hadith mentioned in Bukhari, with 4000 repeats[2]. It took Imam Bukhari 16 years[3] to complete this book. Muhammad ibn Yusuf al-Firbari says Imam Bukhari said that he did not write a single hadith in his saheeh except that he would do ghusl and two rakah of salah before writing it[4].
There is a difference of opinion as to where Imam Bukhari wrote his book. Some have said Basra, some have said Bukhara and others have said Masjid al-Haram. According to Imam al-Nawawi he wrote it in all four of the following; Makkah, Madina, Basra and Bukhara.[5]
Abu Ali Al-Gassani narrates that Imam Bukhari said that he has taken out from his saheeh six hundred thousand ahadith. It is also narrated that Imam Bukhari said that he did not remove from his book except saheeh ahadith, and that which he has left out is more[6]
When Imam Bukhari had completed his saheeh he presented it to Imam Ahmad ibn Hanbal, Yahya ibn Maeen, Ali bin al-Madeeni and others. They testified to its authenticity except for four. The most correct opinion is that these four were the sayings of Imam Bukhari and not hadith[7].
The number of commentaries of Saheeh al-Bukhari exceed hundred[8]. One of the more famous commentaries is Fathul Bari of Imam Ibn Hajar al-Asqalani. There is also the work of Allamah Badruddin al-Ayni entitled Umdat Ul Qari.
The highest sanad in Saheeh al-Bukhari is with three narrators, and the lowest is the hadith of Yajooj and Majooj with nine narrators.[9]
[1] Hadyu al-Saari vol.1 p.8
[2] Hadyu al-Saari vol.2 p.503
[3] Tahzeeb ul-Kamaal vol.24. p.449
[4] Hadyu al-Saari vol.1 p.8
[5] Sharh Bukhari by Imam Nawawi
[6] Hadyu al-Saari vol.1 p.9
[7] Hadyu al-Saari vol.1 p.9
[8] Al-Madkhal p.30
[9] Al-Fawaaid al-Daraari p.72