Musannaf Ibn Abi Shaybah 23759 — Paying in advance (salam) for food

Kulayb said: I asked Sayyiduna Ibn Umar (may Allah be pleased with them both): A man comes to us and makes a salam sale of wheat for a dirham for a fixed term, on the basis that each jarib (a measure) of wheat is one dirham and two jaribs of barley are one dirham (what about this?). He said: That is very good.