Jesus answered their question with a question from everyday life that everyone could answer. No one fasts at a wedding. Matthew Henry says that during the wedding celebration the guests "are merry, and think it becomes them to be so." By putting it this way, Jesus quietly cast Himself as the bridegroom and His disciples as His wedding party. Gill draws the conclusion: it was "very unsuitable for them, and very unreasonable to desire them to fast at such a time." The question presses the hearers to ask not only what the disciples were doing, but who was with them.

Jesus answered His own question at once: "as long as they have the bridegroom with them, they cannot fast" (Mark 2:19). He went on, "But the days will come, when the bridegroom shall be taken away from them, and then shall they fast in those days" (Mark 2:20). He then gave two short pictures: no one sews new cloth on an old garment, and "new wine must be put into new bottles" (Mark 2:21-22). Mark records no reply from the questioners.

"Children of the bridechamber" is a word-for-word rendering of the Greek huioi tou nymphōnos, "sons of the bridechamber." Thayer's lexicon explains them as "the friends of the bridegroom whose duty it was to provide and care for whatever pertained to the bridal chamber." Barnes calls them "the bridemen, or men who had the special care of the bridal chamber, and who were therefore his special friends" (on Matthew 9:14-15). The ESV simply says "wedding guests."

The Greek word for bridechamber appears only three times in the New Testament, all in this saying (Matthew 9:15; Mark 2:19; Luke 5:34). The "bottles" of Mark 2:22 were skins, as Barnes explains on Matthew 9:17, which is why new wine could burst old ones.

Jesus asks this question, and it reveals how He saw Himself. He did not call Himself a teacher whose disciples kept different rules. He called Himself the bridegroom, the One whose presence turns an ordinary day into a celebration. The disciples' joy was not a lack of devotion. It was the right response to who was with them.

But there is a shadow in the picture. "The bridegroom shall be taken away from them" (Mark 2:20). Barnes explains that once the bridegroom is gone, sorrow and fasting fit (on Matthew 9:14-15). Early in Mark, Jesus already speaks of a coming loss, and He ties His followers' fasting to that loss.