Musnad Abu Ya'la al-Mawsili 42:198

Zuhayr narrated to us, Jarir narrated to us, from al-A’mash, from Abu Salih, from Abu Sa’id al-Khudri, who said: There was something between Khalid ibn al-Walid and ‘Abd al-Rahman ibn ‘Awf, so Khalid insulted him. The Messenger of Allah (may Allah bless him and grant him peace) said: "Do not insult anyone among my companions, for if one of you were to spend the equivalent of Uhud [in gold], he would not reach a mudd of one of them, nor half of it."