Musannaf Ibn Abi Shayba 13:3304

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Isra’il narrated to us, from Jabir, from ‘Amir, regarding two men who were disputing over a thing. One of them said to his companion: "If you swear [an oath], then it is yours." He said: "If he swears, then it is his."