And convey good news to those who believe and do good deeds, that they shall have gardens in which rivers flow; whenever they shall be given a portion of the fruit thereof, they shall say: This is what was given to us before; and they shall be given the like of it, and they shall have pure mates in them, and in them, they shall abide.

Allah's Apostle said, "Don't sell gold for gold unless equal in weight, nor silver for silver unless equal in weight, but you could sell gold for silver or silver for gold as you like."