Matthew 6:16-18

“Now whenever you fast, do not make a gloomy face as the hypocrites do, for they distort their faces so that they will be noticed by people when they are fasting. Truly I say to you, they have their reward in full. But as for you, when you fast, anoint your head and wash your face, so that your fasting will not be noticed by people but by your Father who is in secret; and your Father who sees what is done in secret will reward you.