Musnad Abu Ya'la al-Mawsili 2:95

Suwayd ibn Sa'id narrated to us, Malik narrated to us, from Ibn Shihab, from Malik ibn Aws ibn al-Hadathan, that he informed him that he sought an exchange for one hundred dinars. He said: Talhah ibn Ubayd Allah called me, and we reached an agreement on the exchange until he exchanged with me. He took the gold and began turning it over in his hand. He said: "Until my treasurer comes from al-Ghabah," while Umar ibn al-Khattab was listening. Umar said: "No, by Allah, you shall not depart from him until you take [the payment] from him." Then he said: The Messenger of Allah (ﷺ) said: "Gold for gold is usury, except for 'hand to hand' (ha'an bi-ha'), and dates for dates is usury, except for 'hand to hand', and barley for barley is usury, except for 'hand to hand'."