Musannaf Ibn Abi Shayba 13:2940

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Sufyan narrated to us, from ‘Asim al-Ahwal, from Ibn Sirin, who said: Two men came disputing to ‘Ubaydah. He said: "Do you appoint me as an authority over you?" They said: "Yes." So he judged between them.