Matthew 9:14

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

The question came in sorrow while John was in prison, when his disciples were filling their days with mourning and frequent fasts. It grew out of the Jewish view of fasting as an act of merit, with the most rigid observers fasting twice each week. John's disciples themselves followed many rabbinical rules and hoped to be justified by works of the law.

Those who asked had not accepted Jesus as the world's Redeemer as fully as John had, and lacked a clear understanding of Christ's work. They thought He needed to reform His practice because He did not do in every particular as John did. They saw His disciples being molded differently from themselves and from the scribes and Pharisees.

While they were mourning and fasting over John's imprisonment, they saw Jesus sitting and eating with publicans and sinners. Misinterpreting His purpose in doing so, they united with the Pharisees in condemning His practice. In that confusion they wondered whether the Pharisees' criticisms of Jesus had some basis.

The answer was that the children of the bridechamber cannot mourn while the Bridegroom is with them, but they will fast when the Bridegroom is taken from them. Fasting and mourning were not fitting for His disciples because they had the Bridegroom with them as everything to them. They were instead to catch the rays of light from Jesus and learn the spiritual nature of His kingdom and the grace of His character, so they could work when He should leave them.