بُلُوغُ الْمَرَامِ
Bulugh al-Maram 876
Business Transactions
عَنْ أَبِي هُرَيْرَةَ - رضى الله عنه - قَالَ: قَالَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -{ مَطْلُ اَلْغَنِيِّ ظُلْمٌ, وَإِذَا أُتْبِعُ أَحَدُكُمْ عَلَى مَلِيٍّ فَلْيَتْبَعْ } مُتَّفَقٌ عَلَيْهِ [1] .
Narrated Abu Hurairah (RA): Allah's Messenger (ﷺ) said: "Delay in payment by a rich man is injustice. So, if one of you is referred for payment to a wealthy man he should accept the reference." [Agreed upon].
Sunnah.com reference: Book 7, Hadith 118