Musannaf Ibn Abi Shayba 33:263

Yahya ibn Isa narrated to us, from al-A’mash, from Ibrahim, from Hammam, from Hudhayfah, who said: I entered upon Umar while he was sitting on a trunk in his house, talking to himself. I drew near to him and said, "What is it that concerns you, O Commander of the Faithful?" He gestured with his hand and indicated it. I said, "That which concerns you—by Allah, if we were to see in you a matter that we disapprove of, we would straighten you." He said, "By Allah, besides whom there is no god, if you were to see in me a matter that you disapprove of, would you straighten me?" I said, "By Allah, besides whom there is no god, if we were to see in you a matter that we disapprove of, we would straighten you." He rejoiced greatly at that and said, "Praise be to Allah who has placed among you, the companions of Muhammad, one who, if he sees in me a matter that he disapproves of, straightens me."