Musannaf Ibn Abi Shayba 18:470

Abu Bakr narrated to us, he said: Muhammad ibn Abi ‘Adi narrated to us, from Ibn ‘Awn, from Muhammad, who said: I do not know the blood [the right of retaliation for blood] to be for anyone except its people; if they wish, they may sell it, and if they wish, they may gift it, and if they wish, they may seek retaliation.