Musannaf Ibn Abi Shayba 18:18

Abu Bakr narrated to us, he said: Hafs narrated to us, from Ash'ath, from al-Hasan, that Umar and Uthman assessed the blood money (diyah). They left that to the discretion of the giver; if he wishes, he may pay in camels, and if he wishes, he may pay in their monetary value.