Matthew 6:16-18

And whenever you are fasting, do not look gloomy and sour and dreary like the hypocrites, for they put on a dismal countenance, that their fasting may be apparent to and seen by men. Truly I say to you, they have their reward in full already. [Isa. 58:5.] But when you fast, perfume your head and wash your face, So that your fasting may not be noticed by men but by your Father, Who sees in secret; and your Father, Who sees in secret, will reward you in the open.