'Fast' in the Bible

"When any of you fast, never assume gloomy looks as the hypocrites do; for they disfigure their faces in order that it may be evident to men that they are fasting. I solemnly tell you that they already have their reward.

But, whenever you fast, pour perfume on your hair and wash your face,

At that time John's disciples came and asked Jesus, "Why do we and the Pharisees fast, but your disciples do not?"