'Fast' in the Bible

"Moreover when you fast, don't be like the hypocrites, with sad faces. For they disfigure their faces, that they may be seen by men to be fasting. Most certainly I tell you, they have received their reward.

But you, when you fast, anoint your head, and wash your face;

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

Jesus said to them, "Can the friends of the bridegroom mourn, as long as the bridegroom is with them? But the days will come when the bridegroom will be taken away from them, and then they will fast.