Musnad Abu Ya'la al-Mawsili 1:77

Umayyah ibn Bistam narrated to us, Yazid ibn Zuray' narrated to us, Yunus—meaning ibn Ubayd—narrated to us, from Humayd ibn Hilal, from Abdullah ibn Mutarrif, from Abu Barzah, who said: While Abu Bakr was at his work, he became angry with a man from the Muslims, and his anger toward him became very intense. When I saw that, I said, "O Caliph of the Messenger of Allah, shall I strike his neck?" When I mentioned the killing, he turned away from that speech entirely toward something else of that nature. When we dispersed, Abu Bakr sent for me after that and said, "O Abu Barzah, what did you say?" He said, "I forgot what I said." He said, "You said such and such; do you remember what you said?" I said, "No, by Allah." He said, "Do you not see that when you saw me angry at the man, you said, 'Shall I strike his neck, O Caliph of the Messenger of Allah?' Do you not remember that, or were you going to do that?" I said, "Yes, by Allah, and even now, if you command me, I will do it." He said, "Woe to you—or alas for you—by Allah, that is not for anyone after the Messenger of Allah, may Allah bless him and grant him peace."