Musannaf Ibn Abi Shayba 13:40

Ali ibn Mushir narrated to us, from al-Shaybani, from al-Sha'bi, who said: I asked him about a man who enters into a *salam* (forward sale) contract, then takes part of his *salam* as dirhams and part of his *salam* as food. He said: "Do not take anything except your capital, or all of it as food."