Is the aforementioned transaction, which takes place to exchange foreign currency for local currency and involves intermediaries, a prior phone call to determine the price, and later hand-to-hand delivery, considered a usurious transaction?

For the validity of exchanging one currency for another, mutual possession ( قبض ) must take place at the session of the contract. If the two parties to the exchange separate before mutual possession, the exchange is invalid by consensus. The possession of the agent stands in place of the possession of the principal, and agency in exchange was affirmed by Umar and Ibn Umar. The transaction is valid if the buying and selling occur when the agent and the merchant meet, and the prevailing exchange rate at the time of their meeting is what matters, as that is the time of contracting.