The most excellent fasting is to make the human senses and organs, like the eyes, ears, heart, and thoughts, fast together with the stomach. That is, to withdraw them from all unlawful things and from trivia, and to urge each of them to their particular worship.

For example, to ban the tongue from lying, back-biting, and obscene language and to make it fast. And to busy it with activities like reciting the Qur’an, praying, glorifying God’s Names, asking for God’s blessings on the Prophet Muhammad (Upon whom be blessings and peace), and seeking forgiveness for sins. And for example, to prevent the eyes looking at members of the opposite sex outside the stipulated degrees of kinship, and the ears from hearing harmful things, and to use the eyes to take lessons and the ears to listen to the truth and to the Qur’an, is to make other organs fast too. As a matter of fact, since the stomach is the largest factory, if it has an enforced holiday from work through fasting, the other small workshops will be made to follow it easily.

(The Twenty-Ninth Letter - Risale-i.Nur Collection)