Praise be to Allaah.
Trading in currencies in
the manner described is permissible, subject to the condition that the
exchange be completed in the same sitting as the contract is made. It is
permissible to sell riyals for euros, subject to the condition that the
handover take place in the same sitting as the contract is made. It is also
valid to exchange the euros for dollars after that, so long as the same
condition is met. So the profit that is made from this transaction is
permissible. The evidence for that is the words of the Prophet (peace
and blessings of Allaah be upon him): “Gold for gold, silver for silver,
wheat for wheat, barley for barley, dates for dates, salt for salt, like for
like, hand to hand. If the types are different then sell however you like,
so long as it is hand to hand.” Narrated by Muslim, 1587.
It says in Fataawa al-Lajnah al-Daa’imah (13/458)
In exchanges of currency it is essential that the exchange be
completed in the same sitting as the contract is made. It is not permissible
to hand over some straight away and delay some. It is proven that the Prophet (peace and blessings of Allaah be upon him) said: “If the types
are different then sell however you like, so long as it is hand to hand.” End quote.