Sayyiduna Abu Hurairah (may Allah be pleased with him) narrated from the Messenger of Allah (peace and blessings be upon him), he (peace be upon him) said: "Silver should be exchanged for silver in equal amounts and by weight, so whatever is in excess is usury. And gold should be exchanged for gold in equal amounts and by weight, so whatever is in excess is usury. And dates should not be sold until their (ripeness) becomes apparent."