Muhammad ibn Ishaq ibn Rahwayh said: My father related to me:

“Ahmad ibn Hanbal said to me, ‘Come, that I may show you a man whose like has never been seen.’ He then took me to al-Shafiʿi.”

My father added, “Yet al-Shafiʿi himself had never seen anyone comparable to Ahmad ibn Hanbal. Had it not been for Ahmad—and for the way he staked his very life—Islam would have been lost,” a reference to the Mihna.

It is also reported from Ishaq ibn Rahwayh that he said, “Ahmad is a decisive proof between Allah and His creation.”

Muhammad ibn ʿAbduwayh said: I heard ʿAli ibn al-Madini declare, “In my view, Ahmad surpasses Saʿid ibn Jubayr in his own time, because Saʿid had contemporaries who equaled him, whereas Ahmad had none.”

Ibn al-Madini likewise said, “Allah upheld the religion through al-Siddiq on the day of the Ridda, and through Ahmad on the day of the Mihna.”

Abu ʿUbayd observed, “Knowledge has come to rest with four men—foremost among them Ahmad ibn Hanbal, who is the most learned in jurisprudence…,” and he went on to recount the story.

He also said, “I consider the very mention of Ahmad an act of devotion; I have never seen a man more knowledgeable of the Sunnah than he.”

Al-Hasan ibn al-Rabiʿ remarked, “I compare Ahmad ibn Hanbal to none but Ibn al-Mubarak in his demeanor and bearing.”

Al-Tabarani narrated: Muhammad ibn al-Husayn al-Anmati told us: “We were in a gathering attended by Yahya ibn Maʿin and Abu Khaythamah. They began extolling Ahmad ibn Hanbal, whereupon a man protested, ‘Tone it down a little.’ Yahya replied, ‘And is profuse praise of Ahmad objectionable? Were we to occupy all our sittings in praising him, we would still not exhaust his virtues.’”

ʿAbbas transmitted from Ibn Maʿin that he said, “I have never seen anyone like Ahmad.”