'Amr b. Shu'aib, on his father's authority, said that his grandfather reported God’s Messenger as saying, “Both parties in a business transaction have a right to annul it so long as they have not separated unless it is a bargain with the right to annul it attached to it; and one has not the right to separate from the other for fear that he may demand that the bargain be rescinded.” Tirmidhi, Abu Dawud and Nasa’i transmitted it.