Sayyiduna Malik bin Aws bin Al-Hadthan narrates that once I made a transaction of silver in exchange for gold with Sayyiduna Talha (may Allah be pleased with him). Sayyiduna Talha (may Allah be pleased with him) said, "Wait a little, our treasurer will be coming from 'Ghabah'." Upon hearing this, Sayyiduna Umar (may Allah be pleased with him) said, "No! Do not part from him until you have received your due from him, because I heard the Prophet (peace and blessings be upon him) say: 'The exchange of gold for silver is usury, except when it is done hand to hand (on the spot).'"