Silsilat al-Ahadith al-Sahihah

Sayyiduna Bara’ bin ‘Azib (may Allah be pleased with him) narrates that I heard the Messenger of Allah (peace and blessings be upon him) say: “If you are attacked suddenly at night, your slogan (for identification) should be «حم لاينصرون» (Ha Meem – help will not be given to the disbelievers).”