Musannaf Ibn Abi Shayba 18:573

Abu Bakr narrated to us, he said: Abd al-A’la narrated to us, from Ma’mar, from al-Zuhri, he said: There is no retaliation (qisas) for the *amma* (a head wound reaching the membrane of the brain), nor for the *ja’ifa* (a wound reaching the body cavity), nor for the breaking of bones.