Its Rank among the Sunni ḥadīth collections:
Sahih Muslim stands in the second rank after Sahih al-Bukhari; it is the second of the two most reliable books after the Book of Allah. Al-Nawawi says in the introduction to his commentary on Sahih Muslim:

“The soundest compilation in ḥadīth—indeed, in all branches of knowledge—are the two Sahihs compiled by the two exemplar imams, Abu ‘Abd Allah Muhammad ibn Isma‘il al-Bukhari and Abu al-Husayn Muslim ibn al-Hajjaj al-Qushayri, may Allah have mercy on them; no other authored work equals them.”

He further states: “The scholars, may Allah have mercy on them all, unanimously agree that, after the Noble Quran, the most authentic books are the two Sahihs of al-Bukhari and Muslim, and the entire ummah has received them with acceptance. Of the two, al-Bukhari’s compilation is the more authentic and the richer in benefits and insights.”