Sahih Muslim, Mashkul. EIGHT VOLUMES IN TWO.

Sahih Muslim is a collection of hadith compiled by Imam Muslim ibn al-Hajjaj al-Naysaburi. His collection is considered to be one of the most authentic collections of the Sunnah of the Prophet, and along with Sahih al-Bukhari forms the "Sahihain," or the "Two Sahihs." It contains roughly 7500 hadith (with repetitions).
It is highly acclaimed by and considered the second most authentic hadith collection after Sahih al-Bukhari. Out of 300,000 hadith which he evaluated, approximately 4,000 were extracted for inclusion into his collection based on stringent acceptance criteria. Each report in his collection was checked and the veracity of the chain of reporters was painstakingly established. However, it is important to realize that Muslim ibn al-Hajjaj never claimed to collect all authentic traditions as his goal was to collect only traditions that all Muslims should agree on about accuracy.
According to Munthiri, there are a total of 2,200 hadiths (without repetition) in Sahih Muslim. According to Muhammad Ami there are 1,400 authentic hadiths that are reported in other books, mainly the six major hadith collections.