Imam Muslim ibn al Hajjaj of Nishapuri belonged to the Qushayri tribe of Arabia, which played an important part in Islamic history. Many of his clan members had been the Prophet's companions.

After the Muslim conquests, a large number of Arab families migrated and settled in the newly conquered provinces, where many of his tribesmen held important posts, e.g. Kulthum b. Iyaz was governor of Africa. His forefathers too occupied important positions during the time of the four Caliphs. Imam Muslim inherited a large fortune from his father, who was also a well-known traditionist of his time.

Imam Muslim was gifted with great intelligence and a sharp memory. First of all, he studied Arabic literature and other sciences taught in his times. Later on he developed a keen interest in the study of hadith. He began by learning hadith from the great scholars, including Imam Bukhari, who were at that time in Nishapur. This town, situated in a central place enjoyed great prestige at that time. Afterwards, he undertook long journeys to collect traditions from other scholars of repute. He went to most of the important centres of learning in Persia, Mesopotamia, Syria and Egypt, where he attended the lectures of most of the important traditionists of his time, including Ishaq ibn Rahwayh and Imam Ahmad ibn Hambal.

After finishing his studies, he came back to Nishapur and devoted his life to the service of hadith. He died in 261/874 on account of having consumed too many dates. One day he was so engrossed in investigating a particular hadith, that he just did not notice that he had eaten all the dates in the container one by one. Consequently, he took ill and died in 874.

Imam Muslim was of an excellent character-honest, truthful and peace-loving. He wrote many books and treatises on hadith, and other related subjects. The most important of his works is his Sahih. Some scholars have regarded it as the best work on the subject. Imam Muslim examined 300,000 traditions before the completion of this book. Out of his large collection he included only 4000 traditions. One great feature of his book is that he selected only those traditions which were free of all defects and were unanimously accepted by the great hadith scholars.

Imam Muslim strictly observed the principles of the science of hadith. He was even stricter than Imam Bukhari in pointing out the differences between the accounts of various narrators, their character and other details. He shows greater ability in the arrangement of traditions.

Moreover, he wrote a long introduction to his book explaining the principles followed by him as regards the choice of the material for his book.

Thanks to the utmost care having been taken in its completion, the Sahih of Imam Muslim has been acknowledged as one of the most authentic collections of traditions after that of Sahih al Bukhari. So far as the beauty of its arrangement is concerned, it is held superior to Sahih al Bukhari. Although some scholars, including Imam Nasai, held the Sahih of Al Muslim superior to that of al Bukhari, the majority of the scholars have held the latter superior, the main reason being that when Imam Bukhari started working, he had no example before him for such a project. His contribution is very great by the virtue of fact that he managed to save all the authentic traditions by collecting them so painstakingly. On the contrary, Imam Muslim had Sahih al-Bukhari as an example. He had every opportunity to learn from both its salient features as well as its defects. Imam Muslim himself recognized the superiority of his predecessor.

The Sahih of Imam Muslim is regarded as next to Al-Bukhari in accuracy and authenticity. Any tradition which is accepted by both Al-Bukhari and Muslim has been termed as 'agreed upon'. And these 'agreed upon' traditions are considered to be the most reliable.

Imam Muslim has added to his work an introduction to the science of tradition. His work consists of 52 chapters dealing with the common subjects of hadith, such as the five pillars of Islam, marriage, the laws of heredity, war, sacrifice, manners and customs, etc. The book closes with a short chapter on the tafsir (exegesis) of the Quran. The longest chapter, the opening chapter of Sahih Muslim is on Iman.