It is possible for one who fasts not to be rewarded for his fasting. How? When indeed we abstain from foods, but do not abstain from iniquities; when we do not eat meat, but gnaw to pieces the homes of the poor; when we do not become drunkards with wine, but we become drunkards with evil pleasures; when we abstain all the day, but all the night we spend in unchasten shows. Then what is the benefit of abstention from foods, when on the one hand you deprive your body of a selected food, but on the other offer yourself unlawful food?
ST. JOHN CHRYSOSTOM