It is narrated from Sayyiduna Salman al-Farisi (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Hold fast to the night prayer (qiyam al-layl), for it was the way of the righteous before you; it brings you near to Allah, the Mighty and Majestic; it is an expiation for sins; it restrains from wrongdoing; and it drives sickness away from the body."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6129