Is it authentic from Imam Ahmad that he was asked about al-Ma'mun and said: "A disbeliever in Allah the Great"?

Question:
May Allah reward you, Your Eminence, father. We have received many questions, and we present to you what is feasible of them. The questioner asks: Is it authentic from Imam Ahmad (may Allah have mercy on him) that he was asked about al-Ma'mun and said: "A disbeliever in Allah the Great"?

Answer:
This is not authentic from Imam Ahmad, nor did he declare al-Ma'mun a disbeliever. Rather, he feared for al-Ma'mun; he feared for al-Ma'mun and said, "I do not think that Allah will neglect al-Ma'mun, for he has introduced into Islam what is not of it." As for declaring him a disbeliever, I do not know that he declared al-Ma'mun a disbeliever. Nor did he order going out against him, even though he struck him, harmed him, and imprisoned him. He was patient with him and adhered to obedience and submission, and did not go out against him, nor did he incite people to go out against him. Rather, when they came to him asking to go out against him, he rebuked them; he rebuked them, because going out, may Allah protect us, necessitates evils: the shedding of blood, the loss of the word, and the division of the Muslims. This is from his jurisprudence (may Allah have mercy on him), the abundance of his knowledge, his scrupulousness, his mindfulness of Allah, and his advice to the Ummah. He did not have the attitude of these people who champion themselves, saying, "You have it: this is vile, this is a disbeliever, look into it." But the man was a jurist and a great Imam; he was patient and endured, and did not open for the people a door of evil and going out against the one in authority. Yes.