It is narrated from Sayyiduna Ali (may Allah be pleased with him) that once, at night, when we had already lain down on our beds, the Prophet (peace and blessings be upon him) came, placed his blessed feet between me and Fatimah, and taught us to recite these words after lying down on the bed: "Say Subhan Allah thirty-three times, Alhamdulillah thirty-three times, and Allahu Akbar thirty-four times." Sayyiduna Ali (may Allah be pleased with him) says that after that, I never abandoned these words. Someone asked: Not even on the night of Siffin? He replied: Yes! (not even then).