'Fasting' in the Bible

"Whenever you fast, do not be sullen like the hypocrites, for they make their faces unrecognizable in order that they may be seen fasting by people. Truly I say to you, they have received their reward in full!

But [when] you are fasting, {put olive oil on your head} and wash your face

so that you will not be seen by people as fasting, but to your Father who is in secret, and your Father who sees in secret will reward you.

And John's disciples and the Pharisees were fasting, and they came and said to him, "{Why} do the disciples of John and the disciples of the Pharisees fast, but your disciples do not fast?"

And [while] they were serving the Lord and fasting, the Holy Spirit said, "Set apart now for me Barnabas and Saul for the work to which I have called them."

And [when they] had appointed elders for them in every church, [after] praying with fasting, they entrusted them to the Lord, in whom they had believed.