Abdullah bin Abi Bakr (may Allah have mercy on him) narrates from his father that in the letter which the Prophet (peace and blessings be upon him) wrote and gave to Sayyiduna Amr bin Hazm (may Allah be pleased with him) there was: "For a bone-exposing wound (mudihah) there are five camels."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16192