The Pharisees were religious overachievers – they went above and beyond what was ‘required’ of them. Fasting is a great example of this. While the Law of Moses spoke of fasting once a year for the Day of Atonement, the Pharisees took it to a much higher level – they would fast twice a week, on the second and fifth day (Monday and Thursday).
When someone didn’t fast like they did, they would hold it over them to show that they, the Pharisees, were much better than the others were. Jesus’ response was telling. He didn’t get after them for fasting (fasting can be done in a God pleasing way in certain situations). He simply taught them. First, by showing them that there were other more important things the disciples should be doing while Jesus was there than simply fasting. He also, through a parable, showed them that there was something new and greater present, the One who to whom the ceremonial laws pointed forward!
Who is this Jesus? He is the fulfillment of the Old Testament ceremonial Laws. He fulfills the old covenant and establishes a new one.