Is it permissible to pay for a commodity with gold instead of currency, when both parties agree on the price in currency, and the price is paid directly with gold without delay?

If the initial agreement was on a monetary value, and then the sale contract was concluded for the payment of the currency value in gold, there is no issue.

Similarly, there is no objection to concluding a sale contract for a price in cash, and then, at the time of payment, settling it with gold at the day's rate.

However, what is forbidden is purchasing an item with deferred cash, with an agreement to pay it later in gold, due to the condition of immediate exchange (taqabud) in currency exchange (sarf) and the impermissibility of deferment therein.