Guidance on the permissibility of selling wheat for gold on credit, even though both are subject to riba

The questioner : If someone says: If these categories differ, sell as you wish, provided it is hand-to-hand, does this cover the case of selling wheat for dirhams? Is immediate exchange obligatory?

The Shaykh : The apparent meaning of the hadith is: "Sell as you wish." Now, the categories differ: dirhams of silver and wheat. The apparent meaning of the hadith is that immediate exchange is obligatory before separating, so we say yes, this is the apparent meaning of the hadith. However, this apparent meaning is contradicted by what is established from the Prophet (peace and blessings be upon him)
Salam is the advance of the price and the deferral of the item sold, so there is no immediate exchange in it, but rather there is deferral as well. It is said, as the jurists (may Allah have mercy on them) said, that it is not required that one of them be cash for this condition to apply; rather, if one of them is cash, deferral is permissible, whether it matches the other in the operative cause, such as iron according to the view that the operative cause is weight, or does not match it in the operative cause, such as wheat.

The questioner : Is this a known statement, or is there a point to consider? Is it known? No.

The Shaykh : Okay, now we understand that. Is dirhams for food permissible or not permissible? The evidence is the hadith of Salam; dirhams for [wheat] is permissible according to the view that the operative cause is weight, and the evidence is the hadith of Ibn Abbas . It is permissible. So, on this basis, the exception is as follows: whenever the categories of goods subject to riba differ, excess is permissible in them, but deferral is not, except if one of them is cash. If one of them is cash, there is no harm in deferral.