Abu Minhal (may Allah have mercy on him) says that I asked Hazrat Bara bin Azib (may Allah be pleased with him) and Hazrat Zaid bin Arqam (may Allah be pleased with him) about the exchange of currency. They said, "Ask him, he knows better and is more knowledgeable than me," and the other said, "Ask him, he knows better and is more knowledgeable than me." In any case, both of them said that the Noble Prophet (peace and blessings be upon him) forbade the deferred sale and purchase of silver in exchange for gold.