The Ruling on Conditioning a Sale

Question : If he sells it before it is displayed, he has sold something unknown, which constitutes gharar (excessive uncertainty in a contract).

Answer : It is valid. As for the issue of conditioning a sale, there is no harm in it as long as the condition is known, such as if he says, "I sold you my car for ten thousand, if my father is pleased." Then he goes to the father and says, "I am pleased," and the sale is valid, because this does not involve riba (usury or interest), injustice, or a hidden motive.