Sahih al-Bukhari 2140
Narrated Abu Huraira:
Allah's Messenger (ﷺ) forbade the selling of things by a town dweller on behalf of a desert dweller; and 
similarly Najsh was forbidden. And one should not urge somebody to return the goods to the seller so 
as to sell him his own goods; nor should one demand the hand of a girl who has already been engaged 
to someone else; and a woman should not try to cause some other woman to be divorced in order to 
take her place.
حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ، حَدَّثَنَا سُفْيَانُ، حَدَّثَنَا الزُّهْرِيُّ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ قَالَ نَهَى رَسُولُ اللَّهِ صلى الله عليه وسلم أَنْ يَبِيعَ حَاضِرٌ لِبَادٍ، وَلاَ تَنَاجَشُوا، وَلاَ يَبِيعُ الرَّجُلُ عَلَى بَيْعِ أَخِيهِ وَلاَ يَخْطُبُ عَلَى خِطْبَةِ أَخِيهِ، وَلاَ تَسْأَلُ الْمَرْأَةُ طَلاَقَ أُخْتِهَا لِتَكْفَأَ مَا فِي إِنَائِهَا‏.‏