Nawf bin Fizala Bakali, the famou scholar of the early Islamic days says that one night he was with Mola Ali (a.s). In the middle of the night, Imam (a.s) got up from his bed, looked for sometime at the stars and inquired of Nawf whether he was awake. Nawf said I got from my bed replying,
"Yes, Amirul Mo'minin (Commander of the Faithful) ! I am awake".
Mola Ali (a.s) said:
"Nawf! Those are the fortunate people who adopt piety as the principle of their lives and are fully attentive to their welfare for the Hereafter. They accept bare earth as the most comfortable bed and water as the most pleasant drink. They adopt the Holy Qur'an and prayers as their guide and protector and like Prophet Jesus Christ (Isa) they forsake the world and its vicious pleasure. Nawf! Prophet David (Daud) once got up at such an hour in the night and said this was the hour when prayers of everyone who prayed were accepted except of those who forcibly collected revenues or who were scandal- mongers or were persons in the police force of a despotic regime or were musicians".
Ref: Nahjul Balagha (Saying # 104)