Musannaf Ibn Abi Shayba 36:142

Yazid ibn Harun narrated to us, from Ibrahim ibn Sa'd, from his father, from his grandfather, from Abd al-Rahman ibn Awf, who said: "I was in the row on the day of Badr, and I turned to my right and to my left, and behold, there were two young boys, very young in age, and I disliked their presence. One of them said to me, secretly from his companion, 'O uncle, show me Abu Jahl.' I said, 'What do you want with him?' He said, 'I have made a vow to Allah that if I see him, I will kill him.' Then the other said to me, also secretly from his companion, 'O uncle, show me Abu Jahl.' I said, 'And what do you want with him?' He said, 'I have made a vow to Allah that if I see him, I will kill him.' I was not pleased to be in the place of anyone else but them. I said, 'There he is,' and I pointed him out to them. They rushed toward him like two falcons—and they were the sons of Afra—until they struck him."