Sayyiduna Umar bin Khattab (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings of Allah be upon him) said:“If gold is exchanged for gold and it is not hand to hand, then it is usury; if dates are exchanged for dates and it is not hand to hand, then it is usury; if wheat is exchanged for wheat and it is not hand to hand, then it is usury; if barley is exchanged for barley and it is not hand to hand, then it is usury.”