Musannaf Ibn Abi Shayba 20:4

Abu Bakr narrated to us, he said: Muhammad ibn Bishr al-‘Abdi narrated to us, he said: Nafi‘ ibn ‘Umar narrated to us, from Ibn Abi Mulaykah, from Ibn ‘Abbas, that the Messenger of Allah (may Allah bless him and grant him peace) decreed the oath upon the defendant.