Sarf

The exchange of one currency for another, or gold and silver for each other. Based on the hadith on ribawi commodities, the exchange must be hand to hand (spot settlement) and, when the same currency or metal is exchanged, in equal amounts. Different currencies may be exchanged at any agreed rate but still on the spot.

Deferred or forward currency trades, leveraged forex, and most currency derivatives fail the spot requirement, which is why they are generally impermissible. Sarf rules also shape scholarly debate on cryptocurrency, gold investing, and international remittances.

Sarf is why exchanging dollars for euros at a bank counter is permitted and why retail forex trading on margin is not. The rule comes from the Prophet's instruction that gold, silver, and the other ribawi commodities be exchanged like for like and hand to hand; scholars extend gold and silver to modern fiat currencies because they serve the same monetary function. Spot settlement in modern practice means the trade settles within the market's normal period (T+2 for major currency pairs is accepted by most contemporary scholars as constructive possession).

Leveraged forex fails on two counts: the position is never settled, and the leverage is an interest-bearing loan from the broker with rollover charges. The same analysis is central to crypto: scholars who treat Bitcoin as a currency apply Sarf and require spot exchange, which rules out futures and margin trading but permits buying and holding; scholars who treat it as a commodity or asset apply ordinary sale rules. For gold investors, Sarf requires that a purchase be settled, which is satisfied by allocated physical gold and by most scholars for gold ETFs that hold allocated bullion, but not for unallocated accounts or gold futures.

For remittances, wiring dollars that arrive as rupees is a Sarf executed through agency and is permitted as long as the rate is fixed and settlement is prompt.