«الدينار بالدينار لا فضل بينهما والدرهم بالدرهم لا فضل بينهما فمن كانت له حاجة بورق فليصطرفهما بذهب ومن كان له حاجة بذهب فليصطرفها بالورق والصرف هاؤها»
The Prophet (peace and blessings be upon him) said:
"A dinar for a dinar, with no excess between them, and a dirham for a dirham, with no excess between them either. So whoever needs silver, let him exchange gold for it, and whoever needs gold, let him exchange silver for it, and the exchange must be hand to hand (on the spot)."
Hadith Referenceصحیح الجامع الصغیر / حرف الدال / 3423