Sunan an-Nasa'i

It was narrated from Safwan bin 'Abdullah that his two paternal uncles, Salamah and Ya'la, the sons of Umayyah, said: "We went out with the Messenger of Allah on the campaign of Tabuk, and there was a friend of ours with us, who fought with a man from among the Muslims. The man bit him on the forearm, so he pulled it away from his mouth and a tooth fell out. The man came to the Prophet, seeking blood money, but his brother and bite him like a stallion bites, then come and demand blood money? There is no blood money for that." And the Messenger of Allah juddgedit to be invalid