Sunan an-Nasa'i, Book 44, Hadith 55 (In-Book) ⓘ
It was narrated from Ibn 'Umar that the Prophet said: "No one of you should urge someone to cancel a sale he has already agreed upon with his brother so as to sell him his own goods."
أَخْبَرَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، عَنْ مَالِكٍ، وَاللَّيْثِ، - وَاللَّفْظُ لَهُ - عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم أَنَّهُ قَالَ " لاَ يَبِيعُ أَحَدُكُمْ عَلَى بَيْعِ أَخِيهِ " .
also referenced under: Hadith 4503 (Reference) & Volume 5, Book 44, Hadith 4507 (DarusSalam)