Jami` at-Tirmidhi 3725

Narrated Al-Bara:"The Prophet (ﷺ) dispatched two armies and put 'Ali bin Abi Talib in charge of one of them, and Khalid bin Al-Walid in charge of the other. He said: "When there is fighting, then (the leader is) 'Ali." He said: "So 'Ali conquered a fortress and took a slave girl. So Khalid sent me with a letter to the Prophet (ﷺ) complaining about him. So I came to the Prophet (ﷺ) and he read the letter and his color changed, then he said: 'What is your view concerning one who loves Allah and His Messenger, and Allah and His Messenger love him.'" He said: "I said: 'I seek refuge in Allah from the wrath of Allah and the anger of His Messenger, and I am but a Messenger.' So he became silent