Muslim ibn al-Hajjaj al-Qushayri was the author of Sahih Muslim. After al-Bukhari’s al-Jami‘ al-Sahih, Muslim’s al-Jami‘ al-Sahih is the most respected collection of the hadith (the accounts of the words, deeds, and opinions of the Prophet Muhammad) in Islam.
In many ways, Muslim’s Sahih resembles that of al-Bukhari, which has led to comparisons through the ages. Both are roughly the same size; the traditional figures given are that Muslim's work contains twelve thousand hadith with repetitions and three thousand thirty three individual hadith without. Like al-Bukhari, Muslim grouped his hadith according to the legal, theological, or historical issue that they address. In some quarters, his classification and presentation have been regarded as preferable to al-Bukhari's.
Both men were contemporaries and indeed shared many of the same teachers. For reasons that are by no means clear, it is unanimously asserted that al-Bukhari's collection predates that of Muslim. This may well be based on nothing more than a general impression created by the fact that Muslim took some hadith from al-Bukhari, whereas there is no evidence that the reverse ever occurred. Al-Bukhari’s collection is also commonly regarded as superior to Muslim’s as a repository of authentic hadith, although the highly regarded Abu ‘Ali al-Hafiz al-Nisaburi (AH 277/890 CE-349/960) and at least some scholars in North Africa held the opposite opinion.
Muslim’s introduction to his collection is a very perplexing document. Among other things (including what was later interpreted as an attack against al-Bukhari), Muslim states that he included hadith from transmitters of varying degrees of reliability in his Sahih. For later scholars, reason seemed to necessitate that there exclusively be transmitters of the highest standard of reliability in a collection of authentic hadith. It has been argued Muslim meant to extend his work to cover less-authentic hadith but never had a chance to do so. Others felt that the less-reliable transmitters were only found in the isnads of certain non-core hadith, which were included merely to clarify the authentic hadith. Still others have argued that, although Muslim does include hadith from unreliable transmitters, he also knew the same texts from unimpeachable transmitters and chose to include the former because they happened to have shorter lines of transmission.
Muslim also left behind a number of monographs about subjects that were associated with the study of hadith. Of these, his Kitab al-Tamyiz, an account of the actual methods the early authorities used to authenticate hadith, is by far the most significant. There can be no doubt that, when this book receives adequate attention, a number of questions about the great hadith collections will be answered.
Very little is known about Muslim’s life. He was born in Nishapur shortly after 200/816. As was the custom of the day, he traveled extensively throughout the Islamic world to collect his hadith, and it is claimed that he knew three hundred thousand. He died in 261/875 in Nasrabadh, outside of Nishapur, pehaps from eating too many dried dates at one sitting.