God forbid that in the blessed month of Ramadan you should backbite or slander, or in short, sin, and so become polluted by transgression in the presence of the Lord, the Exalted, at His feast. You have been invited during this honorable month to the banquet of God the Almighty, "and you have been invited in it to the feast of Allah," so, get yourself ready for the magnificent feast of the Almighty. At least respect the formal and exoteric manners of fasting. (The true manners of fasting are another matter entirely, and require constant care and effort.) The meaning of fasting is not merely refraining from eating and drinking, one must also keep oneself from sin. This is the primary etiquette of fasting for novices. (The etiquette of fasting for divine people who want to reach the mine of greatness is other than this) You should at least observe the primary etiquette of fasting, and in the same way that you refrain from eating and drinking, you should keep your eyes, ears and tongue from transgression. From now on, keep your tongue from backbiting, slander, speaking bad, and lies, and expel from your hearts all spite, envy, and other ugly satanic attributes. If you are able, cut yourself off from all but Allah. Perform your deeds sincerely and without duplicity. Cut yourselves off from the devils among humans and the Jinn, although we ourselves apparently cannot aspire to reaching such a valuable state of felicity. At least try to see to it that your fast is not accompanied by sin. Otherwise, even if your fast is correct from the point of view of Islamic law, it will not ascend to be accepted by God. There is a big difference between the ascension of one's works and their acceptance on the one hand, and their religious correctness on the other. If, by the end of the blessed month of Ramadan, there is no change in your works and deeds, and your ways and manners are no different than they were before the month of fasting, it is evident that the fast which you were expected to perform was not realized, and that which you have done is no more than a vulgar physical fast.
I repeat, decide during these thirty days of the blessed month of Ramadan to control your tongue, eyes, ears, and all your organs and limbs, and pay constant attention to the judgment of the sharia about the works you intend to do, and the words you intend to speak and the subject you intend to listen to. This is the elementary and outward manner of keeping a fast. At least keep to this outward manner of fasting! If you observe that someone is about to backbite, prevent him and say to him that we have made a covenant that during these thirty days of Ramadan to keep ourselves from prohibited affairs. And if you are not able to keep him from backbiting, leave that session. Do not just sit there and listen. The Muslims must be safe from you.
The Greatest Jihad (Combat with the Self), Text, Page: 22