Matthew 6:16
When you fast, do not be somber like the hypocrites, for they disfigure their faces to show men they are fasting. Truly I tell you, they already have their full reward.
What it says
Jesus forbids fasting that advertises itself through a somber face and visible distress.
What it is doing
It rejects visible grief as the aim of fasting.
In context
16When you fast, do not be somber like the hypocrites, for they disfigure their faces to show men they are fasting. Truly I tell you, they already have their full reward. 17But when you fast, anoint your head and wash your face, 18so that your fasting will not be obvious to men, but only to your Father, who is unseen. And your Father, who sees what is done in secret, will reward you.