Musannaf Ibn Abi Shayba 18:109

Abu Bakr narrated to us, he said: Abu Usamah narrated to us, from Sa'id, from Qatadah, from Sa'id ibn al-Musayyib, he said: The *mudihah* (a wound that exposes the bone) in the head is five [camels], and in the face it is ten.