Musannaf Ibn Abi Shaybah 24821 — A man who pledges something

Al-Rabi' says: I asked Abu Ja'far (may Allah have mercy on him): "I bought food from a man, and he gave me part of it. Then his food ran out and he had nothing left to give me. He said: 'Sell me some of your food so that I can give you (the rest of your share).'" Abu Ja'far said: "Do not even go near this; this is open usury (riba)."