"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."  

عَنِ النَّبِيِّ ﷺ أَنَّهُ قَالَ لاَ يَبِيعُ أَحَدُكُمْ عَلَى بَيْعِ أَخِيهِ  

"Do not urge someone to cancel a sale he has already agreed upon so as to sell him your own goods, unless he bys or changes his mind."  

عَنْ رَسُولِ اللَّهِ ﷺ قَالَ لاَ يَبِيعُ الرَّجُلُ عَلَى بَيْعِ أَخِيهِ حَتَّى يَبْتَاعَ أَوْ يَذَرَ