Allah (swt), the Exalted, said to His Prophet (sw): "And during the night, pray Tahajjud beyond what is obligatory for you, so that your Lord (azj) may raise you to a praised station" (Surah Al-Isra 17:79). Thus, the night prayer (Tahajjud) became an obligation upon the Messenger of Allah (sw) due to the command of Allah (swt): 'And during the night, pray Tahajjud.' For others, however, it remains a Sunnah and a supererogatory act.