Abu Bakr ibn Ishaq al-Subghi: I witnessed two Imams of the Muslims, but I was not granted the opportunity to hear from them, and I mentioned him among them.
Abu Hatim ibn Hibban al-Busti: He mentioned him among the trustworthy and said: One of the Imams in the world who collected and categorized knowledge, and he was the most knowledgeable of his time in matters of differing opinions and the most meticulous in preserving knowledge.
Abu Abd Allah al-Hakim al-Naysaburi: An Imam without dispute.
Ibn Hajar al-Asqalani: Trustworthy Jurist, Memorizer, Imam, Mountain (of knowledge)
Muhammad ibn Ishaq al-Dubusi: He was an ocean of Hadith.
Muhammad ibn Abd al-Hakam al-Masri: He was considered an Imam in our view, so what about in Khurasan!