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 ‏"‏ ‏.‏

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."