Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: Sayyiduna Usamah bin Zaid (may Allah be pleased with them both) informed me that the Messenger of Allah (peace and blessings be upon him) said: "Riba (usury) is only in the case of a loan." Imam Darimi (may Allah have mercy on him) said: That is, (for example) if one pays two dirhams in exchange for one dirham, (then it is riba).