Abu Saʿīd Ḥātim ibn Muḥammad narrated that the ḥadith master Mūsā ibn Hārūn said, “Were all the Muslims to assemble with the sole purpose of appointing another man like Muḥammad ibn Ismāʿīl, they would never manage to do so.”

Abu al-ʿAbbās Muḥammad ibn ʿAbd al-Raḥmān, the jurist al-Daghulī, said: “The people of Baghdad once wrote to al-Bukhārī:
‘The Muslims prosper so long as you remain among them,
but after you no good endures once you are missed.’ ⦗1⦘

Abu Bakr al-Khaṭīb relates: “Abū Zurʿa was asked about Ibn Lahīʿa and replied, ‘Abū ʿAbd Allāh Muḥammad ibn Ismāʿīl abandoned him.’ He was then asked about Muḥammad ibn Ḥumayd and said, ‘Abū ʿAbd Allāh likewise abandoned him.’ When this was reported to Abū ʿAbd Allāh, he remarked, ‘His kindness toward us goes back a long way.’ ⦗2⦘

Al-Khaṭīb also reports that al-ʿAbbās ibn al-Faḍl al-Rāzī, the goldsmith, was asked, “Which of the two is superior, Abū Zurʿa or Muḥammad ibn Ismāʿīl?” He answered, “I met Muḥammad ibn Ismāʿīl between Ḥulwān and Baghdad, travelled one stage with him, and strove to cite a single ḥadith he did not already know, but I could not manage it—whereas I can relate unfamiliar reports to Abū Zurʿa as numerous as the hairs on his head.” ⦗3⦘

Ahmad ibn Sayyār states in his Chronicle: “Muḥammad ibn Ismāʿīl al-Juʿfī pursued knowledge, sat with scholars, journeyed far in search of ḥadith, and he mastered it and became exceptionally discerning in it,”