Is it permissible to buy gold at today's price without taking possession of it, contenting oneself with an agreement with the merchant to have grams of gold with him at the agreed-upon price, regardless of whether the price increases or decreases, with or without specifying the day of possession?

It is impermissible to purchase gold on a deferred basis, whether the price is paid immediately or deferred, and whether the price is in currency, gold, or silver. This is due to the involvement of usury (riba) in such a transaction, based on the Prophet's (peace be upon him) saying: "Gold for gold... hand to hand," and "Gold for gold is usury except if exchanged hand to hand," meaning seized in the same sitting. Paper currencies have the same rulings as gold and silver regarding usury and other matters.