Is it permissible to exchange currency for less than its market price?

Question:
May Allah reward you, Honorable Shaykh. This questioner says: One of the brothers has foreign currency, and the value of this currency is thirteen riyals. So I said to him: I will give you ten riyals, and you give me this currency you have. Is this permissible?

Answer:
If the currencies are different, there is nothing wrong with an increase or decrease. The Messenger (peace and blessings be upon him) said: . So if the type of currency differs, there is nothing wrong with selling it for more or less, provided that the exchange takes place in the meeting. However, if the currency is of the same type, it is not permissible to exchange it; rather, equality and exchange in the meeting are required.