كتاب المساقاة
22  
The Book of Musaqah
(7)
Chapter: The prohibition of a rich man delaying repayment. The validity of Hawalah (Transferal of Debts) and it is recommended to accept transferal of a debt if it is transferred to a rich man
(7)
بَاب تَحْرِيمِ مَطْلِ الْغَنِيِّ وَصِحَّةِ الْحَوَالَةِ وَاسْتِحْبَابِ قَبُولِهَا إِذَا أُحِيلَ عَلَى مَلِيٍّ
Sahih Muslim 1564 a

Abu Huraira (Allah be pleased with him) reported Allah's Messenger (ﷺ) 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.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، ‏.‏ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ مَطْلُ الْغَنِيِّ ظُلْمٌ وَإِذَا أُتْبِعَ أَحَدُكُمْ عَلَى مَلِيءٍ فَلْيَتْبَعْ ‏"‏ ‏.‏
Reference : Sahih Muslim 1564a
In-book reference : Book 22, Hadith 41
USC-MSA web (English) reference : Book 10, Hadith 3796
  (deprecated numbering scheme)