Musannaf Ibn Abi Shayba 13:2524

Abu Bakr narrated to us, he said: Ibn ‘Uyaynah narrated to us, from al-Zuhri, that he heard Malik ibn Aws ibn al-Hadathan saying: I heard ‘Umar saying: The Messenger of Allah (ﷺ) said: "Gold for silver is usury (riba) except if it is hand-to-hand (ha'an wa ha'an). Silver for silver is usury except if it is hand-to-hand. Barley for barley is usury except if it is hand-to-hand. Dates for dates is usury except if it is hand-to-hand."