Sahih al-Bukhari, is one of the Kutub al-Sittah (six major hadith collections) of Sunni Islam. These prophetic traditions, or hadith, were collected by the Persian Muslim scholar Muhammad al-Bukhari, after being transmitted orally for generations. Sunni Muslims view this as one of the three most trusted collections of hadith along with Sahih Muslim and Muwatta Imam Malik. In some circles, it is considered the most authentic book after the Quran.
Hadith in religious use is often translated as 'tradition', meaning a report of the deeds and sayings of Muhammad. The hadith literature does not qualify as primary source material as it was compiled from oral reports that were present in society around the time of their compilation, well after the death of the Prophet Muhammad.
Bukhari's collection which is considered by many traditional religious scholars as the most 'reliable' was compiled two centuries after the death of the Prophet