Gospel of Matthew 6:16-18
Jesus Said: "When you fast, do not look somber as the hypocrites do, for they disfigure their faces to show men they are fasting.
I tell you the truth, they have received their reward in full.
But when you fast, put oil on your head and wash your face, so that it will not be obvious to men that you are fasting,
but only to your Father, who is unseen; and your Father, who sees what is done in secret, will reward you."