Then al-Hakim said: “I heard the ḥadith-master Muhammad ibn Ya‘qub relate that he heard my father say, ‘I saw Muslim ibn al-Hajjaj sitting before al-Bukhari, putting questions to him with the eagerness of a child.’ (1)

He also said: “I heard al-Hasan ibn Ahmad al-Shaybani—the reliable authority—say that he heard Ahmad ibn Hamdun remark, ‘I saw Muhammad ibn Isma‘il at the funeral of Sa‘id ibn Marwan, while Muhammad ibn Yahya al-Dhuhli was asking him about personal names, teknonyms, and hidden defects. Muhammad ibn Isma‘il sped through the answers like an arrow (2), as though he were reciting, “Say: He is Allah, One” (Ikhlas 1).’

Muhammad ibn Khalid al-Mutawwi‘i of Bukhara informed us; Musabbih ibn Sa‘id al-Bukhari narrated to us; he said: I heard ‘Abd Allah ibn ‘Abd al-Rahman al-Samarqandi say, ‘I have met the scholars of the Hijaz and of both Iraqs, yet among them I never saw anyone more comprehensive in knowledge than Muhammad ibn Isma‘il.’ (3)

Muhammad ibn Hamdun ibn Rustum said: ‘I heard Muslim ibn al-Hajjaj come to al-Bukhari and say, “Allow me to kiss your feet, O teacher of teachers, master of the ḥadith scholars, and physician of ḥadith in its hidden defects.”’ (4)

Abu ‘Isa al-Tirmidhi said: ‘In neither Iraq nor Khurasan have I ever encountered anyone more knowledgeable than Muhammad ibn Isma‘il concerning hidden defects, chronology, and the evaluation of chains of transmission.’ (5)