I said: Abū Jaʿfar is not reliable.

Ibn ʿAdī related: I heard Aḥmad ibn Muḥammad ibn Saʿīd who said, “Al-Ḥaḍramī told me, ‘I heard Abū Bakr ibn Abī Shaybah, and he was asked, “Who among those you have met had the strongest memory?”’
He answered, ‘I have never seen anyone with a better memory than Abū Zurʿah al-Rāzī.’”

Ibn al-Muqriʾ said: ʿAbd Allāh ibn Muḥammad ibn Jaʿfar al-Qazwīnī narrated to us, “I heard Muḥammad ibn Isḥāq al-Ṣāghānī say, ‘Abū Zurʿah is comparable to Aḥmad ibn Ḥanbal.’” (1)

ʿAlī ibn al-Ḥusayn ibn al-Junayd remarked, “I have never seen anyone more knowledgeable about the hadith of Mālik ibn Anas—both those with continuous chains and those that are broken—than Abū Zurʿah, and the same applies to the other disciplines.” (2)

Ibn Abī Ḥātim said: My father was asked about Abū Zurʿah, and he replied, “He is an imam.” (3)

ʿUmar ibn Muḥammad ibn Isḥāq al-Qaṭṭān reported: I heard ʿAbd Allāh ibn Aḥmad ibn Ḥanbal say that he heard his father declare, “No one who crossed the bridge was more proficient in jurisprudence than Isḥāq ibn Rāhūyah, and no one had a better memory than Abū Zurʿah.” (4)

Ibn ʿAdī also said: I heard Abū Yaʿlā al-Mawṣilī state, “Whenever we heard someone praised for his memorization, actually meeting him proved less impressive than what was reported—except Abū Zurʿah al-Rāzī. Seeing him was more awe-inspiring than his reputation. He had committed to memory the hadith on juristic chapters, the names of teachers, and Qurʾānic exegesis; through his own selections at Wāsiṭ we wrote down six thousand hadith.” (5)