Musannaf Ibn Abi Shayba 18:450

Abu Bakr narrated to us, he said: Muhammad ibn Bakr narrated to us, from Ibn Jurayj, he said: 'Amr ibn Shu'ayb said: Abu Bakr decreed regarding a man's breast, if its nipple is lost, [a compensation of] five camels. And he decreed regarding a woman's breast [a compensation of] ten camels if only the nipple of her breast is affected. But if it is cut off from its base, then fifteen camels.