It is narrated from Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him), he says: It is not permissible to conduct a forward sale (salam) in wheat, common barley, or huskless barley until the grain has dried. Nor is this sale permissible in grapes, olives, and the like, until these things have ripened well. Nor is it permissible to sell cash gold for deferred silver, or cash silver for deferred gold. Imam Ahmad said: This narration is not marfu‘ (attributed directly to the Prophet).