the battle had actually started. protected by armour and shields, ‘utbah bin rabi‘a stepped forth between his brother shaibah and his son al-waleed bin ‘utbah from the lines of quraish and hurled maledictions at the muslims. three young men of the helpers came out against them: ‘awf and mu‘wwadh — the sons of harith, and ‘abdullah bin rawaha. but the makkans yelled that they had nothing to do with them. they wanted the heads of their cousins. upon this the prophet [pbuh] asked ‘ubaidah bin al-harith, hamzah — his uncle, and his cousin ‘ali [r] to go forward for the combat. the three duels were rapid. hamzah killed shaibah, while ‘ali killed al-waleed.[mishkat 2/343] ‘ubaidah was seriously wounded but, before he fell, hamzah fell upon ‘utbah and with a sweep of his sword, cut off his head. ‘ali and hamzah carried ‘ubaidah back with his leg cut off. he died four or five days later of a disease in the bile duct.
‘ali was possessed of a deep conviction that allâh’s words were revealed:
"these two opponents (believers and disbelievers) dispute with each other about their lord." [al-qur'an 22:19]
these verses were revealed in connection with men of faith who confess their lord and seek to carry out his will (i.e. muhammad [pbuh]’s followers at badr battle), and men who deny their lord and defy him (the people of quraish).