It is reported from Abu Majidah (may Allah have mercy on him): I fought with a boy, and I cut off his ear, or he cut off my ear. Abu Bakr (may Allah be pleased with him) came to us, and we were brought before him; we presented our dispute to him, and he sent us to Umar (may Allah be pleased with him). He said: This matter has reached (the level of) retaliation; call a cupper to cut (in retaliation) from him. He said two or three times: I heard the Messenger of Allah (peace and blessings be upon him) say: "I gave my maternal aunt a slave boy as a gift, hoping that she would be blessed in him, and I said to her: Do not hand him over to a cupper, a butcher or a goldsmith."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الإجارة / 11693