Sahih al-Bukhari 2287
Sahih al-Bukhari · Book 38: Transferance of a Debt from One Person to Another (Al-Hawaala) · Al-Hawala (the transference of a debt from one person to another. It is an agreement whereby a debtor is released from a debt by another becoming responsible for it). Can Hawala be rejected by the creditors after accepting it?
Narrated Abu Huraira:
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ ، أَخْبَرَنَا مَالِكٌ ، عَنْ أَبِي الزِّنَادِ ، عَنِ الأَعْرَجِ ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " مَطْلُ الْغَنِيِّ ظُلْمٌ، فَإِذَا أُتْبِعَ أَحَدُكُمْ عَلَى مَلِيٍّ فَلْيَتْبَعْ " .
The Prophet (ﷺ) said, "Procrastination (delay) in paying debts by a wealthy man is injustice. So, if your debt is transferred from your debtor to a rich debtor, you should agree."