Kutub al-Sittah

The Kutub al-Sittah (the six books) are the primary ahadith collections in Sunni Islam. They consist of, , , , and. The collections total tens of thousands of ahadith.

The first two collections, Sahih Bukhari and Sahih Muslim, are considered the most authentic; the word Sahih itself means "authentic." Authenticity decreases for each collection thereafter, although Islamic maddhabs (schools of religious law or fiqh) have differed on which of the non-Sahih collections are more or less trustworthy.

Some Muslims, notably Quranists, consider all ahadith to be bid'ah (prohibited religious innovation), fabricated, or otherwise unacceptable.