Abu al-Husayn Muslim ibn al-Hajjaj al-Qushayri al-Naysaburi was born in Nishapur, in the Abbasid province of Khorasan (in present-day northeastern Iran); sources differ on the year, giving 202, 204, or 206 AH (roughly 817–822 CE). He travelled across the Arabian Peninsula, Egypt, Iraq, and Syria to gather hadith from scholars in each, then settled back in his home city, where he met al-Bukhari, studied under him, and remained his friend for the rest of his life. According to al-Khatib al-Baghdadi, he undertook the book at a student's request, Ahmad ibn Salama al-Naysaburi; its original title, al-Musnad al-Sahih al-Mukhtasar, is usually shortened, like al-Bukhari's, to Sahih Muslim. He died in Nishapur in 261 AH (875 CE) and was buried in its suburb Nasarabad.
He accepted a hadith only when its chain of transmission was unbroken back to a companion of Muhammad, passing at every link through at least two reliable narrators; he sorted narrators into three tiers by memory and character and set aside any whose honesty had been disputed. His commentator al-Nawawi singled out a further care: Muslim, he wrote, places each hadith in one suitable spot together with all of its chains and variant wordings, rather than letting them appear scattered — a presentation later commentators have contrasted with [[BUK|Sahih al-Bukhari]]'s practice of entering a hadith's differing wordings separately, under whichever chapter each wording's point illustrates.
How many hadith the book holds depends, as with [[BUK|Sahih al-Bukhari]], on who is counting and how repeats are handled. Kâtip Çelebi and Siddiq Hasan Khan each arrived at 7,275; Muhammad Fu'ad Abd al-Baqi, counting without repetition, at 3,033; Mashhur ibn Hasan Al Salman at 7,385, or 7,395 counting the ten hadith in Muslim's own introduction; other estimates put the total anywhere from about 5,500 to 7,500. Al-Jawzaqi counted 2,326 hadith shared, essentially word for word, with Sahih al-Bukhari. This corpus's own count is a further number again: 57 books and 7,563 numbered hadith, which is simply the shape of the digital edition it was drawn from, not a claim to reproduce any one print numbering exactly.
The Arabic text here is the classical matn, in the public domain. Beneath it in the reader sits an English translation, drawn from the fawazahmed0/hadith-api's eng-muslim edition and aligned hadith-for-hadith with the Arabic so the two can be read as a pair — the same companion arrangement this corpus uses for [[BUK|Sahih al-Bukhari]] and for its Qur'an translations. Which published English translation that file itself descends from has not been pinned down on this corpus's side, which is why its licence is marked under review rather than public domain outright; the Arabic above it carries no such uncertainty.