Sahih Muslim | Book 10 | Hadith Number 3796

Narrated by Abu Huraira (Allah be pleased with him)
Abu Huraira (Allah be pleased with him) reported Allah's Messenger (may peace be upon him) as saying: Delay (in the payment of debt) on the part of a rich man is injustice, and when one of you is retired to a rich man, he should follow him.