Matthew 9:14

Some of John's disciples came to Jesus saying, "Why is it that we and the Pharisees fast frequently [i.e., going without food and/or drink for religious reasons], but your disciples do not fast [at all]?"

Matthew 11:2

Now while still in prison, John [the Immerser] heard about the things Christ was doing, [so] he sent [word] through his disciples

John 3:25

[About then] a dispute arose between John's disciples and a Jew over ceremonial cleansing.

John 4:1

PM, if Jewish time were meant].

Matthew 6:16

"In addition, when you fast [i.e., go without food and/or drink for religious reasons], do not be like the hypocrites with long faces, for they go around with gloomy expressions on their faces in order to advertise that they are fasting. It is true when I say to you, these people have [already] received their reward.

Matthew 11:18-19

For when John came, he did not eat or drink [on festive occasions] and people said, 'He is dominated by an evil spirit.'

Mark 2:18-22

Now John's disciples and the Pharisees were fasting, [i.e., going without food and/or drink for religious reasons]. Some people came and asked Jesus, "Why do John's disciples and the Pharisees' disciples fast, but your disciples do not?"

Luke 5:33-39

Then they said to Jesus, "John [the Immerser's] disciples fast frequently [i.e., going without food and/or drink for religious reasons] and they offer earnest prayer requests, and the disciples of the Pharisees do the same things. But your disciples eat and drink."

Luke 18:9-12

Then Jesus told this parable to certain ones who were relying on their own goodness and putting everyone else down:

Treasury of Scripture Knowledge

Summary

Then came to him the disciples of John, saying, Why do we and the Pharisees fast oft, but thy disciples fast not?

Bible References

Why

Matthew 6:16
"In addition, when you fast [i.e., go without food and/or drink for religious reasons], do not be like the hypocrites with long faces, for they go around with gloomy expressions on their faces in order to advertise that they are fasting. It is true when I say to you, these people have [already] received their reward.
Matthew 11:18
For when John came, he did not eat or drink [on festive occasions] and people said, 'He is dominated by an evil spirit.'
Mark 2:18
Now John's disciples and the Pharisees were fasting, [i.e., going without food and/or drink for religious reasons]. Some people came and asked Jesus, "Why do John's disciples and the Pharisees' disciples fast, but your disciples do not?"
Luke 5:33
Then they said to Jesus, "John [the Immerser's] disciples fast frequently [i.e., going without food and/or drink for religious reasons] and they offer earnest prayer requests, and the disciples of the Pharisees do the same things. But your disciples eat and drink."
Luke 18:9
Then Jesus told this parable to certain ones who were relying on their own goodness and putting everyone else down: