Sayyiduna Ali (may Allah be pleased with him) narrates: Sayyidah Fatimah (may Allah be pleased with her) came to the service of the Prophet (peace and blessings be upon him) to ask for a servant. The Prophet (peace and blessings be upon him) said: Shall I not guide you (the narrator is in doubt, perhaps these are the words) or shall I not teach you something that is better for you than that? When you go to your bed (to sleep), recite Subhan Allah, Allahu Akbar, and La ilaha illallah thirty-three times each.

Sayyiduna Ali (may Allah be pleased with him) narrates: Since I heard this from the Prophet (peace and blessings be upon him), I have never abandoned this practice. People asked: Not even on the night of the Battle of Siffin? He replied: Not even on the night of the Battle of Siffin (did I abandon this practice).