ʿUmar ibn Shabīb al-Muslī said, “I once saw Abū Isḥāq after he had gone blind; Isrāʾīl was pushing him along, while his son Yūsuf was leading him by the hand.

Ibn ʿUyaynah related that ʿAwn ibn ʿAbd Allah asked Abū Isḥāq, ‘What strength is left in you?’ He replied, ‘I can still recite Sūrat al-Baqarah in a single rakʿah.’ ʿAwn responded, ‘Your good remains, and your bad has departed.’

ʿAlī ibn al-Madīnī said, ‘Knowledge was safeguarded for the ummah by six men: for the people of Kūfa—Abū Isḥāq and al-Aʿmash; for the people of Basra—Qatādah and Yaḥyā ibn Abī Kathīr; and for the people of Medina—al-Zuhrī.’ (1)

Abū Bakr ibn ʿAyyāsh remarked, ‘I never heard Abū Isḥāq criticize anyone at all, and whenever he mentioned a Companion it was as though, in his eyes, that Companion was the very best of them.’

Fudayl ibn Marzūq said, ‘I heard Abū Isḥāq say, “I wish I could come out of my knowledge with neither loss nor gain.”’

Aḥmad ibn Ḥanbal and Yaḥyā ibn Maʿīn both stated, ‘Abū Isḥāq is trustworthy.’

Yaḥyā ibn Maʿīn further said, ‘The narrations of Zakariyā ibn Abī Zāʾidah, Zuhayr, and Isrāʾīl from Abū Isḥāq are of roughly equal reliability; nevertheless, his foremost pupils are Shuʿbah and al-Thawrī.’

Jarīr, transmitting from Mughīrah, said, ‘No one corrupted the hadith of Kūfa except Abū Isḥāq and al-Aʿmash.’

I say: The statements of contemporaries about one another are not admissible as evidence. Abū Isḥāq’s hadith is relied upon in the authoritative works of Islam, and a number of his elevated isnāds have reached us.

Yaḥyā ibn Saʿīd al-Qaṭṭān said, ‘Abū Isḥāq died in 127 AH, on the day Ḍaḥḥāk ibn Qays entered Kūfa in full control.’