Musannaf Ibn Abi Shayba 18:925

Abu Bakr narrated to us, he said: Abu Usama narrated to us, from Ibn Jurayj, he said: Ata’ informed me, he said: Safwan ibn Ya’la ibn Umayyah informed me, from his father, he said: I had a hired worker, and he fought with a man, so one of them bit the hand of the other. Ata’ said: Safwan indeed informed me which of them bit the other. The one who was bitten pulled his hand away from the mouth of the biter, and he pulled out one of his front teeth. They came to the Prophet, peace be upon him, and he declared his front tooth to be uncompensated (i.e., he did not grant blood money or retaliation for it).