It is narrated from Hazrat Imran bin Husain (may Allah be pleased with him) that a man bit another man's hand, and when the latter pulled his hand away, the biter's front teeth broke and fell out. Both of them brought this dispute to the service of the Prophet (peace and blessings be upon him), so the Prophet (peace and blessings be upon him) declared it invalid and said: "One of you bites his brother like a bull."