It is narrated from Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) that he said: "There are three things which, had the Prophet (peace and blessings be upon him) fully explained them to us, would have been dearer to me than this world and everything in it: (first,) the caliphate, (second,) kalalah, and (third,) usury (riba)." This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), and they did not record it.