The Prophet ﷺ said: A townsman must not sell for a man from the desert, even if he is his brother or father. Abu Dawud said: Anas b. Malik said: It was said: A townsman must not sell for a man from the desert. This phrase carries a broad meaning. It means that the (the townsman) must not sell anything for him or buy anything for him.  

أَنَّ النَّبِيَّ ﷺ قَالَ لاَ يَبِيعُ حَاضِرٌ لِبَادٍ وَإِنْ كَانَ أَخَاهُ أَوْ أَبَاهُ  

the Prophet forbade a town-dweller to sell for a desert- dweller, even if he was his father or brother. (Sahih )  

أَنَّ النَّبِيَّ ﷺ نَهَى أَنْ يَبِيعَ حَاضِرٌ لِبَادٍ وَإِنْ كَانَ أَبَاهُ أَوْ أَخَاهُ  

Messenger of Allah ﷺ said, "You should not try to cancel the purchases of one another (to get a benefit thereof), and do not go ahead to meet the caravan (for buying the goods) (but wait) till it reaches the market."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لاَ يَبِيعُ بَعْضُكُمْ عَلَى بَيْعِ بَعْضٍ وَلاَ تَلَقَّوُا السِّلَعَ حَتَّى يُهْبَطَ بِهَا إِلَى السُّوقِ  

Ibn ʿAbbas said, "Messenger of Allah ﷺ said, 'Do not go to meet the caravans on the way (for buying their goods without letting them know the market price); a town dweller should not sell the goods of a desert dweller on behalf of the latter.' I asked Ibn ʿAbbas, 'What does he mean by not selling the goods of a desert dweller by a town dweller?' He said, 'He should not become his broker.' "  

قَالَ رَسُولُ اللَّهِ ﷺ لاَ تَلَقَّوُا الرُّكْبَانَ وَلاَ يَبِيعُ حَاضِرٌ لِبَادٍ قَالَ فَقُلْتُ لاِبْنِ عَبَّاسٍ مَا قَوْلُهُ لاَ يَبِيعُ حَاضِرٌ لِبَادٍ قَالَ لاَ يَكُونُ لَهُ سِمْسَارًا  

Ibn ʿAbbas said, "The Prophet ﷺ forbade the meeting of caravans (on the way) and ordained that no townsman is permitted to sell things on behalf of a bedouin." I asked Ibn ʿAbbas, "What is the meaning of his saying, 'No townsman is permitted to sell things on behalf of a bedouin.' " He replied, "He should not work as a broker for him."  

عَنِ ابْنِ عَبَّاسٍ ؓ نَهَى رَسُولُ اللَّهِ ﷺ أَنْ يُتَلَقَّى الرُّكْبَانُ وَلاَ يَبِيعَ حَاضِرٌ لِبَادٍ قُلْتُ يَا ابْنَ عَبَّاسٍ مَا قَوْلُهُ لاَ يَبِيعُ حَاضِرٌ لِبَادٍ قَالَ لاَ يَكُونُ لَهُ سِمْسَارًا  

Messenger of Allah 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.  

نَهَى رَسُولُ اللَّهِ ﷺ 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  

Messenger of Allah ﷺ forbade (1) the meeting of the caravan (of goods) on the way, (2) and that a residing person buys for a bedouin, (3) and that a woman stipulates the divorce of the wife of the would-be husband, (4) and that a man tries to cause the cancellation of a bargain concluded by another. He also forbade An-Najsh (see Hadith 824) and that one withholds the milk in the udder of the animal so that he may deceive people on selling it.  

نَهَى رَسُولُ اللَّهِ ﷺ عَنِ التَّلَقِّي وَأَنْ يَبْتَاعَ الْمُهَاجِرُ لِلأَعْرَابِيِّ وَأَنْ تَشْتَرِطَ الْمَرْأَةُ طَلاَقَ أُخْتِهَا وَأَنْ يَسْتَامَ الرَّجُلُ عَلَى سَوْمِ أَخِيهِ وَنَهَى عَنِ النَّجْشِ وَعَنِ التَّصْرِيَةِ  

One amongst you should not enter into a transaction when another is bargaining.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لاَ يَبِعْ بَعْضُكُمْ عَلَى بَيْعِ بَعْضٍ  

A believer is the brother of a believer, so it is not lawful for a believer to outbid his brother, and he should not propose an engagement when his brother has thus proposed until he gives it up.  

أَنَّهُ سَمِعَ عُقْبَةَ بْنَ عَامِرٍ عَلَى الْمِنْبَرِ يَقُولُ إِنَّ رَسُولَ اللَّهِ ﷺ قَالَ الْمُؤْمِنُ أَخُو الْمُؤْمِنِ فَلاَ يَحِلُّ لِلْمُؤْمِنِ أَنْ يَبْتَاعَ عَلَى بَيْعِ أَخِيهِ وَلاَ يَخْطُبَ عَلَى خِطْبَةِ أَخِيهِ حَتَّى يَذَرَ