It is narrated from Sayyiduna Uthman (may Allah be pleased with him) that I heard the Messenger of Allah (peace and blessings be upon him) say once: "I know a word that if any servant says it, believing in it with his heart as truth, the fire of Hell will become forbidden for him." Sayyiduna Umar (may Allah be pleased with him) said to him: "Shall I tell you what that word is?" That word is sincerity, which Allah made obligatory upon His Prophet and his companions (may Allah be pleased with them). This is the same word of piety that the Prophet (peace and blessings be upon him) repeatedly presented before his uncle Abu Talib at the time of his death, that is, the testimony of the oneness of Allah.