Benefit no. 61:
Dhikr (remembering Allah) gives a person strength so that he can do with dhikr that which he cannot do without it. I saw wonders in the strength of Shaykh al-Islam Ibn Taymiyah in walking, speech, courage and writing. He used to write in one day what a scribe would write in a week, or more. The troops saw his amazing strength in war. The Prophet (peace and blessings of Allaah be upon him) taught his daughter Faatimah and ‘Ali (may Allaah be pleased with them) to recite tasbeeh thirty-three times every night when they went to bed, and to recite tahmeed thirty-three times, and to recite takbeer thirty-four times, when she asked him for a servant and complained to him about the hardship of grinding corn, working and serving (her family). He taught her that and said: “It is better for you than a servant.” It was said: The one who persists in doing that will find strength in his body that will make him independent of the need for a servant.
Ibn al-Qayyim in al-Waabil al-Sayyib (p. 77)