Matthew 6:16-18 New King James Version (NKJV)
Fasting to Be Seen Only by God
16 “Moreover, when you fast, do not be like the [a]hypocrites, with a sad countenance. For they disfigure their faces that they may appear to men to be fasting. Assuredly, I say to you, they have their reward. 17 But you, when you fast, anoint your head and wash your face, 18 so that you do not appear to men to be fasting, but to your Father who is in the secret place; and your Father who sees in secret will reward you [b]openly.