Matthew 6:16-18

16 "When you fast, stop looking sad like hypocrites. They put on sad faces to make it obvious that they're fasting. I can guarantee this truth: That will be their only reward.

17 When you fast, wash your face and comb your hair.

18 Then your fasting won't be obvious. Instead, it will be obvious to your Father who is with you in private. Your Father sees what you do in private. He will reward you.