What is the ruling on trading in futures contracts, such as taking one kilogram of copper on the condition that two kilograms be returned later, and is this permissible considering that copper is not a usurious commodity?

It is permissible to buy copper with other commodities on credit, or to exchange one kilogram of it for two kilograms without deferment, because it is not among the usurious items.

However, it is not permissible to lend copper with the condition of an increase, or to exchange it with its own kind at a differential with deferment; because a loan is repaid in kind, and stipulating an increase in it is unanimously forbidden usury.

So, if one lends something that is measured by volume or weight and stipulates more than it, it is not permissible by agreement.

The preponderant opinion is that exchanging items of the same kind on credit with an increase is forbidden; because it is in the meaning of a loan with an increase. So, if one lends a pound to be returned as two pounds, it is not permissible. And selling a pound for two pounds on credit is in the meaning of a loan with an increase.

Summary: It is not permissible to lend copper or anything else with an increase, by agreement of the jurists. It is not permissible to sell copper for copper on credit with an increase, according to the preponderant opinion; because it is in the meaning of a loan with an increase.