Messenger of Allah ﷺ said, "Do not urge somebody to return what he has already bought (i.e. in optional sale) from another seller so as to sell him your own goods."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لاَ يَبِيعُ بَعْضُكُمْ عَلَى بَيْعِ أَخِيهِ  

Messenger of Allah ﷺ said, "Do not go forward to meet the caravan (to buy from it on the way before it reaches the town). And do not urge buyers to cancel their purchases to sell them (your own goods) yourselves, and do not practice Najsh. A town dweller should not sell the goods for the desert dweller. Do not leave sheep unmilked for a long time, when they are on sale, and whoever buys such an animal has the option of returning it, after milking it, along with a Sa of dates or keeping it. it has been kept unmilked for a long period by the seller (to deceive others).  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لاَ تَلَقَّوُا الرُّكْبَانَ وَلاَ يَبِيعُ بَعْضُكُمْ عَلَى بَيْعِ بَعْضٍ وَلاَ تَنَاجَشُوا وَلاَ يَبِيعُ حَاضِرٌ لِبَادٍ وَلاَ تُصَرُّوا الْغَنَمَ وَمَنِ ابْتَاعَهَا فَهْوَ بِخَيْرِ النَّظَرَيْنِ بَعْدَ أَنْ يَحْتَلِبَهَا إِنْ رَضِيَهَا أَمْسَكَهَا وَإِنْ سَخِطَهَا رَدَّهَا وَصَاعًا مِنْ تَمْرٍ  

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