Musannaf Ibn Abi Shayba 18:507

Abu Bakr narrated to us, he said: Abu Usama narrated to us, from Muhammad ibn ‘Amr, from ‘Umar ibn ‘Abd al-‘Aziz, he said: The blood money (aq) of a slave is according to his price, like the blood money (aq) of a free man is according to his diyah.