Is it permissible to exchange metal riyals for paper riyals with a difference?

Question:
What is your opinion if a man gives a person ten paper riyals in Saudi currency, and the person returns to him in exchange nine new metal riyals in Saudi currency as well? Is this riba (usury or interest)? It is known that riba is an increase without compensation, and taking an increase without compensation. However, he took it in paper and returned its equivalent in metal.

Answer:
This requires consideration, and the believer should not do it; because it is riyal for riyal, he should not do it, but rather ten for ten. If it were by meaning, some scholars hold that metal is a different type, like gold and silver. So if he sells this for this hand-to-hand, even if this is more than this, because the currency of metal is not the currency of paper, like gold with silver and wheat with barley, there is no harm in the increase, but it must be hand-to-hand and they must take possession of it. This is a possible view, but the choice for the believer is not to do it, because this is a riyal and this is a riyal, except that this is from one material and this is from another material. This is the point of difference. The one who permitted it compared it to gold with silver, and wheat with barley, because it is a face of a person. And the one who forbade it said he knows that their outcome is one and their name is one, all of it is riyal.