Matthew 6:16-18 - The Sermon On The Mount: How To Fast
16 And when you fast, be not like the hypocrites, of a sad countenance; for they disfigure their faces that they may appear to men to fast. I tell you truly, they have their reward. 17 But when you fast, anoint your head, and wash your face, 18 that you may not appear to men to fast, but to your Father in secret; and your Father who sees in secret shall reward you.