Is it permissible to exchange Saudi Riyals for US Dollars when there is a bank guarantee that will be disbursed after two months, and are Riyals considered a commodity that is purchased in this transaction?

Selling riyals for dollars is permissible, provided that the exchange takes place in the same session of the contract and there is no deferment. Riyals are not a commodity; rather, they are a price for commodities. The aforementioned transaction is impermissible because it is based on "lend me and I lend you," which means the investor lends a sum to the bank for the bank to lend him double that amount. Other prohibitions may also be involved, such as borrowing with usury or assisting a usurious bank.