Musannaf Ibn Abi Shaybah

Hazrat Umar narrates that the Messenger of Allah, peace and blessings be upon him, said: "Wheat for wheat is usury, except if it is hand to hand (i.e., on the spot). And barley for barley is usury, except if it is hand to hand (i.e., on the spot)."

Hazrat Ubadah bin Samit narrates that the Messenger of Allah, peace and blessings be upon him, said: Barley, when exchanged for barley, should be equal and paid on the spot.

It is narrated from Hazrat Abu Saeed Khudri that the Messenger of Allah, peace and blessings be upon him, said: Wheat for wheat will be exchanged equally and in cash (sale), and barley for barley will be given equally and in cash. And it is mentioned regarding (Imam) Abu Hanifa's opinion that: he used to say that there is no harm in selling absent wheat in exchange for present wheat.