'Fasting' in the Bible

John's disciples and the Pharisees were fasting, and they came and asked him, "Why do John's disciples and the disciples of the Pharisees fast, but your disciples don't fast?"

If I send them away fasting to their home, they will faint on the way, for some of them have come a long way."

He said to them, "This kind can come out by nothing, except by prayer and fasting."