Musannaf Ibn Abi Shayba 13:1765

Abu Bakr narrated to us, he said: Hafs narrated to us, from Musa ibn Ubaydah, from Abdullah ibn Dinar, from Ibn Umar, that he was asked about a man who pledges a collateral and says: "If I do not bring it to you by such and such [time], then it is yours." He said: "He does not have the right to that."