Sunan Ibn Majah, Volume 3, Book 12, Hadith 2172 (DarusSalam) ⓘ
lt was narrated from Abu Hurairah that the Prophet said: "A man is not to undersell his brother, nor is he to fry to outhaggle his brother."
حَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، حَدَّثَنَا سُفْيَانُ، عَنِ الزُّهْرِيِّ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ ـ صلى الله عليه وسلم ـ قَالَ " لاَ يَبِيعُ الرَّجُلُ عَلَى بَيْعِ أَخِيهِ وَلاَ يَسُومُ عَلَى سَوْمِ أَخِيهِ " .
also referenced under: Hadith 2172 (Reference) & Book 12, Hadith 2256 (In-Book)