Musannaf Ibn Abi Shayba 13:2979

Abu Bakr narrated to us, he said: Jarir narrated to us, from ‘Ata’ ibn al-Sa’ib, from Ibn Mughaffal, regarding a man who has a debt owed to him by another man, and he (the debtor) denies it, then he (the creditor) gains power over some of his (the debtor's) wealth. He said: He should not oppose him (i.e., he should not take it without permission); he should fulfill his trust.