Is it permissible to purchase dollars in installments at a price higher than the market price, provided that payment is made in Iraqi dinars?

Exchanging currencies is called sarf, and it involves two types of riba (usury): riba al-fadl (usury of surplus) and riba an-nasi’ah (usury of delay). The Islamic Fiqh Academy has ruled that paper currencies are subject to the same rulings as gold and silver regarding riba and other matters. When exchanging one currency for another (such as dollars for dinars), immediate possession (taqabud) at the time of the contract is a condition. Selling on installments is not permissible because it leads to riba an-nasi’ah. Taqabud is achieved either actually or constructively by the transfer of the currency from one party's account to the other party's account.