Sunan Ibn Majah
2403
Sahih+3

It was narrated from Abu Hurairah that the Messenger of Allah (ﷺ) said:“(Wrongdoing) is when a rich man takes a long time to repay a debt, and if one of you is referred to a rich man (to collect a debt), he should accept that referral.”

SahihAl-Albani
SahihMuhammad Fouad Abd al-Baqi