Abu Dawud Book 34, Hadith Number 4567.
Chapter : On a man who fights against another man who defends himself from him.
Narated By N/A : Safwan b. Ya’la, on his father’s authority, said : A servant of mine fought with a man and bit his hand and he drew away his hand. (One of) his front teeth fell out. So he came to the Prophet (may peace be upon him) who imposed no retaliation for his tooth, saying: Do you intend that he leaves his hand in your mouth so that you crunch it like a mate camel? He said: Ibn Abi Mulaikah told me on the authority of his grandfather that Abu Bakr (Allah be pleased with him) imposed no retaliation on him for it, saying : May his tooth go away.