Musannaf Ibn Abi Shayba 18:82

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Ibn Abi Layla, from ‘Ikrimah bin Khalid, from a man from the family of ‘Umar, who attributed it to the Prophet (marfu’an), he said: "In the *munqilah* (a head wound that breaks the bone and displaces it), there are fifteen camels, or the equivalent of that in gold or silver."