A notable Imaam in the field of Asmaa ur-Rijaal, Imaam Yahya ibn Ma’een (D. 233H) said:

“The people say that I should become like Ahmed bin Hanbal, no by Allaah, I can never become like him”
[Al-Jarh wat Ta’deel: 1/298, Chain Saheeh]

Abu al-Abbaas Muhammad bin al-Husayn bin Abdur Rahmaan alAnmaati rahimahullah (D. 293H) said:

“We were in a gathering in which Yahya ibn Ma’een, Abu Khaythamah Zuhayr bin Harb, and a group of Major Scholars were present. They were praising Ahmed bin Hanbal and mentioning his virtues, so a man said: Do not exceed in saying such things. Yahya ibn Ma’een said: Is too much praise of Ahmed bin Hanbal a denouncing act? Even if we started praising him in (all) our gatherings, we will still not be able to completely describe his virtues.”
[Hilyat al-Awliyaa: 9/169, 170, Chain Saheeh; Taareekh Baghdaad:4/421, Chain Saheeh]

Imaam Yahya ibn Ma’een said:

“I have not seen anyone similar to Ahmed bin Hanbal; we have adopted his companionship (Friendship) since 50 years. He never showed any proud to us for whatever righteousness and goodness he possessed”
[Hilyat al-Awliyaa: 9/181, Chain Saheeh]

Muhaddith Abu Ja’far Muhammad bin Haaroon al-Makhrami rahimahullah (D. 265H) said:

“When you see a man demeaning Ahmed bin Hanbal then know that he is a misguided innovator”
[Al-Jarh wat Ta’deel: 1/309, Chain Saheeh]

Muhaddith Ahmed bin Abdullah bin Yoonus al-Yarboo’ee al-Koofi rahimahullah (D. 227H) said:

“There is a Palace in Jannah in which no one will enter except a Prophet, or a Siddeeque (Truthful person), or Muhakkam fi Nafsihi (a person firm in his self)”

It was asked: “Who is Muhakkam fi Nafsihi”

So he replied: “Ahmed bin Hanbal is Muhakkam fi Nafsih”
[Al-Jarh wat Ta’deel: 1/310, Chain Saheeh]

This proves that Ahmed bin Yoonus rahimahullah considered Imaam Ahmed bin Hanbal to be a Jannati. This is a very huge Tawtheeq, because being a Jannati is a very big Tawtheeq.

Note: Considering someone a Jannati without Wahy (Revelation) is based on Dhann, Qiyaas, and Personal Tahqeeq; but it is not permissible to take evidence from it.

Taken from the works of Shaykh Zybayr Ali Zai, translated by Raza Hassan, the book can be downloaded from here