Matthew 6:16-18

“And when you fast, do not put on a sad face as the hypocrites do. They neglect their appearance so that everyone will see that they are fasting. I assure you, they have already been paid in full. When you go without food, wash your face and comb your hair, so that others cannot know that you are fasting—only your Father, who is unseen, will know. And your Father, who sees what you do in private, will reward you.