Matthew 9:14-17

About Fasting
See parallels at Mk 2:18-22 and Lk 5:33-39.
v.14 The disciples of John the Baptist asked Jesus why his disciples do not fast like the Pharisees and themselves. On fasting, see 6:16-18. Zealous Jews fasted twice a week (Mon. & Thurs.). The OT law required one fast a year on the day of atonement. Fasting was to be accompanied by deep personal reflection, prayer, and sorrow for sin. Jesus himself fasted (4:2) and after his ascension the disciples often fasted (e.g., Acts 13:3 and 14:23).
v.15 Jesus explained that the bridegroom's friends do not fast when he is with them, but rather when he is taken away (Is 53:8). 'Bridegroom' was a Jewish metaphor for God (Hos 2:16-23). The arrival of the kingdom of God was to be a time of celebration like a marriage ceremony. For the disciples to fast when Jesus was with them would be inappropriate.
v.16-17 Jesus gives two examples (parables, Lk 5:36) that showed that the coming kingdom of God cannot be contained within the old religious system. You don't put a patch of unshrunk cloth on an old garment and you don't put new wine in old wineskins. New wine is put into fresh wineskins that will stretch as the new wine ferments and expands. Jesus' teaching and kingdom must be poured into new forms, the old just won't do.

Read Matthew 9:14-17