It is narrated from Sayyiduna Imran bin Husayn (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "When a man has a right owed to him by another man and he defers it until its appointed term, it is charity for him; and if he defers it even after its term, then for every day there is charity for him."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15694