Musnad Ahmad 30:3217

Muhammad ibn Ja'far narrated to us, he said: Sa'id narrated to us, from Qatadah, from Khallas, from Abu Rafi', from Abu Hurairah, that two men disputed over an animal, and neither of them had evidence. The Messenger of Allah, peace and blessings of Allah be upon him, commanded them to draw lots for the oath, whether they liked it or disliked it.