صحيح البخاري

Narrated `Imran bin Husain:

A man bit another man's hand and the latter pulled his hand out of his mouth by force, causing two of his incisors (teeth) to fall out. They submitted their case to the Prophet, who said, "One of you bit his brother as a male camel bites. (Go away), there is no Diya (Blood-money) for you."