Abu Bakr bin Muhammad bin Amr bin Hazm narrates from his father, and he from his grandfather, that the Prophet (peace and blessings be upon him) wrote a letter to the people of Yemen in which the obligations, the sunnahs and the blood monies were mentioned, and which Amr bin Hazm (may Allah be pleased with him) carried. It also contained: "A man will be killed in return for a woman."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15905