Musnad Abu Ya'la al-Mawsili 160:43

Abu Abd al-Rahman al-Adhrami narrated to us, Ishaq bin Yusuf narrated to us, from Sa'id, from Qatadah, from Khallas, from Abu Rafi', from Abu Hurayrah, from the Prophet, may Allah bless him and grant him peace: That two men disputed over a sale, and there was no evidence between them. So the Messenger of Allah, may Allah bless him and grant him peace, commanded them to draw lots for the oath, whether they liked it or disliked it.