Abu Bakr Marroozi (rahimahullah) once explained the character of Imaam Ahmed (rahimahullah) by mentioning the following:

Abu ‘Abdillah, Imaam Ahmed bin Hambal (rahimahullah), would not behave ignorantly, and if any person behaved ignorantly towards him, he would exercise tolerance and forbearance and would say, “Allah Ta‘ala is sufficient for me.” He would not harbor malice for anyone, nor would he act on impulse. He was extremely humble, displayed excellent character and was always seen smiling. He was soft in his approach when interacting with people and was never found to be harsh. If he liked any person, then his love would be for the sake of Allah Ta‘ala, and if he disliked some person, then his dislike would be for the sake of Allah Ta‘ala. If any aspect of Deen was violated, he would become extremely angry for the sake of Allah Ta‘ala. He would tolerate and endure the harm and inconvenience which was caused to him by his neighbors.

(Siyar A’laam min Nubalaa 11/220-221)