As-Suyuti in "Medicine of the Prophet" said, " Know then that moderate exercise is a most potent means of preserving health. It warms the organs and dissolves waste products and renders the body light and active. The time for this is after the descent of the food from the stomach. It accomplishes this in five or six hours, more or less according to the constitution of the individual and of the food. By moderate exercise is meant exercise which makes the skin red and glow. When sweating begins, then it is proper to cease. That which increases the sweat is called heavy exercise.