Abu ʿAbd Allah al-Ḥākim transmitted that Muḥammad ibn ʿAbd al-Wahhāb al-Farrāʾ said:
“Muslim ibn al-Ḥajjāj was among the foremost scholars of the people and a vast repository of knowledge.”

Al-Ḥākim also said: “I heard Abū al-Faḍl Muḥammad ibn Ibrāhīm say—I heard Aḥmad ibn Salamah say—
‘I saw Abū Zurʿah and Abū Ḥātim give precedence to Muslim ibn al-Ḥajjāj, above the other shaykhs of their time, in recognizing what is authentic.’ ”

He then listed the writings of the Imām of the people of ḥadith, Muslim—may Allah have mercy on him: the book al-Musnad al-Kabīr arranged according to the narrators (I do not think anyone ever heard it directly from him); the book al-Jāmiʿ ʿalā al-Abwāb, a portion of which I have seen in his own handwriting; the book al-Asmāʾ (1) wa-l-Kunā (Names and Patronymics); the book al-Musnad al-Ṣaḥīḥ (the Authentic Musnad); the book al-Tamīz (Critical Distinction); the book al-ʿIlal (Hidden Defects); the book al-Wuḥdān (Single Chains); the book al-Afrād (Singular Reports); the book al-Aqran (Peers); the book Suʾālātihi Aḥmad ibn Ḥanbal (His Questions to Aḥmad ibn Ḥanbal); the book ʿAmr ibn Shuʿayb; the book al-Intifāʿ bi-Uhub al-Sibāʿ (Benefiting from the Hides of Predatory Animals); the book Mashāyikh Mālik (The Teachers of Mālik); the book Mashāyikh al-Thawrī (The Teachers of al-Thawrī); the book Mashāyikh Shuʿbah (The Teachers of Shuʿbah); the book Man Laysa Lahu illā Rāwin Wāḥid (Those Who Have Only a Single Narrator); the book al-Mukhaḍramūn (Those who lived in both the pre-Islamic and Islamic eras); the book Awlād al-Ṣaḥābah (Children of the Companions); the book Awhām al-Muḥaddithīn (Errors of the ḥadith scholars); the book al-Ṭabaqāt (Biographical Strata); and the book Afrād al-Shāmiyyīn (Unique Reports of the Syrians).

Al-Ḥākim went on to list other works of his that I have not recorded here.

Aḥmad ibn Salamah said: “I heard Muslim say, ‘When Ibn Jurayj uses the phrases ‘he narrated to us,’ ‘he informed us,’ and ‘I heard,’ there is nothing on earth more reliable than that.’ (2)”

Makkī ibn ʿAbdān said: “I heard Muslim say, ‘Even if the people of ḥadith were to write for two hundred years, their material would still revolve around this Musnad.’ (3)”