Mukhtasar Bukhari

`Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates that` those who used to sell grain during the time of the Prophet (peace and blessings of Allah be upon him) without measuring or weighing it, I saw that they were beaten because they were not to sell it until they had taken it to their homes (warehouses and other places of storage).

Narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings of Allah be upon him) forbade that anyone should sell grain before taking possession of it (i.e., before it reaches his store, shop, warehouse, etc.). Ibn Abbas (may Allah be pleased with them both) was asked the reason for this (prohibition), so he replied: This is like selling money for money, because the grain is not delivered at that time (until it comes into his store, warehouse, or shop, etc.).

Ameer-ul-Mu'mineen Umar bin Khattab (may Allah be pleased with him) narrates from the Noble Prophet (peace and blessings be upon him) that he said: "Selling gold for gold, wheat for wheat, dates for dates, and barley for barley is usury, except when it is equal for equal and hand to hand, then it is permissible. (Note: Selling 24-carat gold for 22-carat gold in equal weight is also usury.)"