مسند أحمد

Malik bin 'Aws bin al-Hadathan heard 'Umar bin al Khattab رضي الله عنه say: The Messenger of Allah (ﷺ) ﷺ said ­- and on one occasion Sufyan said: ['Umar] heard the Messenger of Allah (ﷺ) ﷺ say ­ “Gold for silver is riba unless it is exchanged on the spot [lit. ‘this for that'), wheat for wheat is riba unless it is exchanged on the spot, barley for barley is riba unless it is exchanged on the spot, dates for dates is riba unless it is exchanged on the spot.”