Muslim ibn al-Hajjaj in the context of "Six major Hadith collections"

Kutub al-Sittah (Arabic: ٱلْكُتُب ٱلسِّتَّة, romanized: al-Kutub al-Sitta, lit. 'the Six Books'), also known as al-Sihah al-Sitta (Arabic: الصحاح الستة, romanized: al-Ṣiḥāḥ al-Sitta, lit. 'the Authentic Six') are the six canonical hadith collections of Sunni Islam. They were all compiled in the 9th and early 10th centuries, roughly from 840 to 912 CE and are thought to embody the Sunnah of Muhammad.

The books are the Sahih of al-Bukhari (d. 870), the Sahih of Muslim ibn al-Hajjaj (d. 875), the Sunan of Abu Dawud (d. 889), the Sunan of al-Tirmidhi (d. 892), the Sunan of al-Nasa'i (d. 915), and the Sunan of Ibn Majah (d. 887 or 889) as the sixth book, though some (particularly the Malikis and Ibn al-Athir) instead listed the Muwatta of Malik ibn Anas (d. 795) as the sixth book, and other scholars list Sunan of al-Daraqutni (d. 995) as the sixth book. Sunan ibn Majah largely won out as the sixth canonical book because its content has less overlap with the other five compared with its two contenders.

Sahih Muslim (Arabic: صحيح مسلم, romanized: Ṣaḥīḥ Muslim) is the second hadith collection of the Six Books of Sunni Islam. Compiled by Islamic scholar Muslim ibn al-Ḥajjāj (d. 875) in the musannaf format, the work is valued by Sunnis, alongside Sahih al-Bukhari, as the most important source for Islamic religion after the Qur'an.

Sahih Muslim contains approximately 5,500 - 7,500 hadith narrations in its introduction and 56 books. Kâtip Çelebi (died 1657) and Siddiq Hasan Khan (died 1890) both counted 7,275 narrations. Muhammad Fuad Abdul Baqi wrote that there are 3,033 narrations without considering repetitions. Mashhur ibn Hasan Al Salman, a student of Albanian Islamic scholar Al-Albani (died 1999), counted 7,385 total narrations, which, combined with the ten in the introduction, add up to a total of 7,395. Muslim wrote an introduction to his collection of hadith, wherein he clarified the reasoning behind choosing the hadith he chose to include in his Sahih.