Narrated Abu Hurairah:It was narrated that Abu Hurairah said: "The Messenger of Allah said: 'Do not artificially inflate prices, a resident should not sell for a Bedouin, a man should not offer more for something that has already been bought by his brother, no one should propose marriage to a woman when someone else has already proposed to her, and no woman should try to bring about the divorce of her sister, in order to deprive her of the blessings that she has.'"
أَخْبَرَنَا مُحَمَّدُ بْنُ مَنْصُورٍ، وَسَعِيدُ بْنُ عَبْدِ الرَّحْمَنِ، قَالاَ حَدَّثَنَا سُفْيَانُ، عَنِ الزُّهْرِيِّ، عَنْ سَعِيدٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم وَقَالَ مُحَمَّدٌ عَنِ النَّبِيِّ صلى الله عليه وسلم " لاَ تَنَاجَشُوا وَلاَ يَبِعْ حَاضِرٌ لِبَادٍ وَلاَ يَبِعِ الرَّجُلُ عَلَى بَيْعِ أَخِيهِ وَلاَ يَخْطُبْ عَلَى خِطْبَةِ أَخِيهِ وَلاَ تَسْأَلِ الْمَرْأَةُ طَلاَقَ أُخْتِهَا لِتَكْتَفِئَ مَا فِي إِنَائِهَا " .
Nesai
The Book of Marriage • Hadith 3239