Matthew 6:16-18

16Jesus then said, ‘You may decide to fast for some time. But do not look sad so that people know you are doing a special thing. Hypocrites want people to see how good they are. They make their faces dirty. Then other people can see that they are fasting. I tell you this: people have praised them and that is the only gift that they will get.

17But when you fast for some time, you should wash your face. Make your hair look nice.

18Then other people will not know that you are doing a special thing. But God, your Father, will know. You do not see him but he sees what you do secretly. He will give you good things in return.