The Messenger of Allah ﷺ as saying: Delay in payment (of debt) by a rich man is injunctive, but when one of you is referred to a wealthy man, he should accept the reference.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ مَطْلُ الْغَنِيِّ ظُلْمٌ وَإِذَا أُتْبِعَ أَحَدُكُمْ عَلَى مَلِيءٍ فَلْيَتْبَعْ