It is narrated from Hazrat Anas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) used to prepare to attack the enemy at the time of dawn and would listen attentively; if he heard the sound of the adhan from there, he would stop, otherwise he would attack. One day, in the same manner, 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." Then when the man said "Ashhadu an la ilaha illallah," the Prophet (peace and blessings be upon him) said, "You have been saved from the fire of Hell."