Sa'd bin Iyas al-Bajali (may Allah have mercy on him) said: Sayyiduna Abdullah (bin Mas'ud) (may Allah be pleased with him) used to permit selling one dirham for two dirhams and one dinar for two dinars. Then he returned to Madinah and went to Sayyiduna Umar, Sayyiduna Ali (may Allah be pleased with them both) and the other Companions of the Messenger of Allah (peace and blessings be upon him), and they forbade him from that. When he came back, I saw him going around among the money-changers saying: "Woe to you, O people! Do not consume usury (riba), and do not buy one dirham for two dirhams, nor one dinar for two dinars."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8545