This is made up from the eating of only what is lawful, from scrupulous observance, from refraining from what is doubtfully allowed, from the control of all bad external emotions and the keeping in check of all internal feelings, from the governing of oneself by wisdom, from the careful preservation of secrets, and from humble supplication to Allah (all Honour & Glory be His) for preservation from the evils of one's own lusts and one's own devil.
Said Bilal: These evils are removed from you by worship of Allah by night, for this was the habit of good men who came before you and is a preventive of sin and renders you close to Allah. It is an expiation of evil deeds and drives away disease from the body. This saying is reported by al-Tirmidhi.
ANOTHER PRESCRIPTION