Muwatta Imam Malik (Riwayat Ibn al-Qasim)

Malik bin Aws bin Hadathan al-Nasri (may Allah be pleased with him) narrates that he wanted to exchange one hundred dinars. He says that Sayyiduna Talha bin Ubaidullah (may Allah be pleased with him) called me, so we bargained with each other until our deal was finalized. He (Talha, may Allah be pleased with him) began turning the dinars over in his hand and then said: "Wait until my treasurer comes from the forest (al-Ghabah)." Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) was listening to our conversation. Then Umar bin al-Khattab (may Allah be pleased with him) said: "By Allah! Do not separate from him (Talha, may Allah be pleased with him) until you take the money from him." The Messenger of Allah (peace and blessings be upon him) said: "Gold for gold is usury except when it is hand to hand, and silver for silver is usury except when it is hand to hand, and wheat for wheat is usury except when it is hand to hand, and dates for dates is usury except when it is hand to hand, and barley for barley is usury except when it is hand to hand."