Abu Dawud Book 8, Hadith Number 2659.
Chapter : Not known.
Narated By Ali ibn AbuTalib : (At the battle of Badr) Utbah ibn Rabi’ah came forward followed by his son and his brother and cried out: Who will be engaged in single combat? Some young men of the Helpers responded to his call. He asked: Who are you? They told him. He said: We do not want you; we, in fact, want only our cousins. The Prophet (PBUH) said: Get up Hamzah get up Ali; get up Ubaydah ibn al-Harith. Hamzah went forward to Utbah, I went forward to Shaybah; and after two blows had been exchanged between Ubaydah and al-Walid, they wounded one another severely; so we turned against al-Walid and killed him, and we carried Ubaydah away.