Here's mentions of fasting in the New Testament (not exhaustive):
Mat 4:2
And having fasted forty days and forty nights, afterward He was hungry.
Mat 6:16-18
“Moreover, when you fast, do not become gloomy, like the hypocrites, for they disfigure their faces that they may appear to men to be fasting. Assuredly I say to you, that they receive their reward in full.
But you, when you fast, anoint your head and wash your face,
so that you do not appear to men to be fasting, but to your Father who is in secret; and your Father, who sees in secret, will reward you.
Mat 9:14-15 (paralleled in Mark 2 and Luke 5)
Then the disciples of John approached Him, saying, “Why do we and the Pharisees fast often, but Your disciples do not fast?”
And Jesus said to them, “Can the groomsmen 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.
Mat 17:23
However, this kind does not go out except by prayer and fasting.”
Luke 2:37
and she was a widow of about eighty-four years, who did not depart from the temple, but served God with fastings and prayers night and day.
Acts 13:2-3
Now as they were ministering to the Lord and fasting, the Holy Spirit said, “Now separate to Me Barnabas and Saul for the work to which I have called them.”
Then, fasting and praying, and laying their hands on them, they sent them away.
Acts 14:23
And having chosen elders for them in every church, and having prayed with fasting, they commended them to the Lord in whom they had believed.
1Co 7:5
Do not deprive one another, except by mutual agreement, and that for a season, so that you may devote yourselves to fasting and prayer; and come together again, lest Satan tempt you because of your lack of self-control.
2Co 6:4-5 (similar in 2Co 11:27)
We give no occasion for offense in anything, lest the ministry be blamed,
but in everything commending ourselves as ministers of God: in much endurance, in tribulations, in hardships, in distresses,
in stripes, in imprisonments, in disturbances, in labors, in sleepless nights, in fastings;