Sahih Bukhari Voluume 003, Book 50, Hadith Number 887.

Narated By Abu Huraira : Allah’s Apostle forbade: 1. The meeting of the caravan (of goods) on the way.
2. A residing person buys for a bedouin.
3. A woman stipulates the divorce of the wife of the would-be husband.
4. 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.