'Fast' in the Bible

"When you fast, do not look sullen like the hypocrites, for they make their faces unattractive so that people will see them fasting. I tell you the truth, they have their reward.

When you fast, put oil on your head and wash your face,

Then John's disciples came to Jesus and asked, "Why do we and the Pharisees fast often, but your disciples don't fast?"

Jesus said to them, "The wedding guests cannot mourn while the bridegroom is with them, can they? But the days are coming when the bridegroom will be taken from them, and then they will fast.