It is narrated from Hazrat Anas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) listened attentively and heard a man saying "Allahu Akbar, Allahu Akbar." The Prophet (peace and blessings be upon him) said, "He is upon the sound nature (fitrah)." Then when he said "Ashhadu an la ilaha illallah," the Prophet (peace and blessings be upon him) said, "You have been saved from the fire of Hell."