Musannaf Ibn Abi Shayba 18:727

Abu Bakr narrated to us, he said: Abd al-Rahim ibn Sulayman narrated to us, from Muhammad ibn Ishaq, from Amr ibn Shu’ayb, from his father, from his grandfather, from the Prophet, peace and blessings of Allah be upon him, who said: "The blood money (diyah) of the disbeliever is half the blood money of the believer."