Malik bin Aws (may Allah have mercy on him) said: I came forward saying: Who will buy dirhams? Talhah (may Allah be pleased with him) said: Show us the gold, (and wait) until our treasurer comes, then come and take your silver. Sayyiduna Umar (may Allah be pleased with him) said: Never! By Allah, you must either return his gold to him or hand over his silver to him, for I heard the Messenger of Allah (peace and blessings be upon him) say: "Selling gold for silver is usury, selling wheat for wheat is usury, barley for barley, and selling dates for dates is usury — except in a hand-to-hand exchange." Qutaybah said: Talhah bin Ubaydullah (may Allah be pleased with him) was with Sayyiduna Umar bin al-Khattab (may Allah be pleased with him), and he said: The Messenger of Allah (peace and blessings be upon him) said this.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10508