Narrated Abu Huraira:
Allah’s Apostle 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.
Sahih Bukhari, Volume 3, Book50, Number 887