Matthew 6:16-18

“Whenever you fast, don’t be gloomy like the hypocrites. For they disfigure their faces   so that their fasting is obvious to people. Truly I tell you, they have their reward. But when you fast, put oil on your head and wash your face,   so that your fasting isn’t obvious to others but to your Father who is in secret. And your Father who sees in secret will reward you.