Musannaf Ibn Abi Shaybah 22739 — A man making a salam contract

Muhammad bin Zayd (may Allah have mercy on him) said: I said to Sayyiduna Ibn Umar (may Allah be pleased with them both): Sometimes a man makes a salam sale with another for a thousand dirhams or thereabouts, and says: If you give me wheat, the deal is for such an amount; and if you give me barley, it is for such an amount. He (may Allah be pleased with him) said: He should state a separate price for each kind among them. If he gives you the very thing in which you made the salam contract, well and good; otherwise, take back your capital from him.