Sayyiduna Uthman Ghani (may Allah be pleased with him) narrates from Sayyiduna Umar bin Khattab (may Allah be pleased with him) that the Prophet Muhammad (peace and blessings be upon him) said: "I know of a word—whoever servant recites this word with a sincere heart and dies upon it, Allah Almighty will make the Hellfire forbidden for him." That word is: "La ilaha illallah" (There is no god but Allah).