Musannaf Ibn Abi Shayba 13:1499

Abu Bakr narrated to us, he said: Abbad bin al-Awwam narrated to us, from Hajjaj, from Uthman, the nephew of Shurayh, that he said: If one acts contrary [to the conditions] regarding a trust (wadi'ah) or a hired item (kira'), then he is a guarantor.