Abu Huraira (Allah be pleased with him) reported Allah's Apostle (ﷺ) as having forbidden a dweller of the town selling the merchandise of a villager or outbidding in a sale (in order that another might fall into a snare), or a person making the proposal of marriage when his brother has already made such a proposal, or entering into a transaction when his brother has already entered; and a woman asking the divorce of her sister in order to deprive her of what belongs to her. 'Amr made this addition:" The person should not purchase in opposition to his brother."
وَحَدَّثَنِي عَمْرٌو النَّاقِدُ، وَزُهَيْرُ بْنُ حَرْبٍ، وَابْنُ أَبِي عُمَرَ، قَالَ زُهَيْرٌ حَدَّثَنَا سُفْيَانُ، بْنُ عُيَيْنَةَ عَنِ الزُّهْرِيِّ، عَنْ سَعِيدٍ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم نَهَى أَنْ يَبِيعَ حَاضِرٌ لِبَادٍ أَوْ يَتَنَاجَشُوا أَوْ يَخْطُبَ الرَّجُلُ عَلَى خِطْبَةِ أَخِيهِ أَوْ يَبِيعَ عَلَى بَيْعِ أَخِيهِ وَلاَ تَسْأَلِ الْمَرْأَةُ طَلاَقَ أُخْتِهَا لِتَكْتَفِئَ مَا فِي إِنَائِهَا أَوْ مَا فِي صَحْفَتِهَا . زَادَ عَمْرٌو فِي رِوَايَتِهِ وَلاَ يَسُمِ الرَّجُلُ عَلَى سَوْمِ أَخِيهِ .
Muslim
The Book of Marriage • Hadith 61