St John Chrysostom: On Fasting

I speak not of such fast as most persons keep. But of real fasting; not merely abstinence from meats, but from sins as well. For the nature of a fast is such that it does not suffice to deliver those who practice it unless it is done according to a suitable law.

So that when we have gone through the labour of fasting we do not lose the crown of fasting, we must understand how and in what manner it is necessary to conduct the business since the Pharisee also fasted, but afterward went away empty and destitute of the fruit of fasting. The publican did not fast, and yet he was accepted in preference to him who had fasted in order that you may learn that fasting is unprofitable unless all other duties accompany it.

...

Let the mouth also fast from disgraceful speeches and railings. For what does it profit if we abstain from fish and fowl and yet bite and devour the brothers and sisters. The evil speaker eats the flesh of his brother and bites the body of his neighbour. Because of this Paul utters the fearful saying:

"If you bite and devour one another take heed that you are consumed by one another"
                      (Gal.5:15).

You have not fixed your teeth in his flesh, but you have fixed your slander in his soul and inflicted the wound of evil suspicion, and you have harmed in a thousand ways yourself and him and many others, for in slandering your neighbour you have made him who listens to slander worse, for should he be a wicked person, he becomes more careless when he finds a partner in his wickedness. And should he be a just person, he is tempted to arrogance and gets puffed up, being led on by the sin of others to imagining great things concerning himself. Besides this, you have struck at the common welfare of the Church herself, for all those who hear you will not only accuse the supposed sinner, but the entire Christian community ... I desire to fix three precepts in your mind so that you may accomplish them during the fast: to speak ill of no one, to hold no one for an enemy, and to expel from your mouth altogether the evil habit of swearing.

This article appeared in Lychnos March 2008