Matthew 9:16-17

The substitution of νησ. τεύουσιν for πενθεῖν, in the close of Matthew 9:15, implicitly suggested a principle which is now explicitly stated in parabolic form: the great law of congruity; practice must conform to mood; the spirit must determine the form. These sayings, apparently simple, are somewhat abstruse. They must have been over the head of the average Christian of the apostolic age, and Luke's version shows that they were diversely interpreted. Common to both is the idea that it is bootless to mix heterogeneous things, old and new in religion. This cuts two ways. It defends the old as well as the new; the fasting of John's disciples as well as the non-fasting of Christ's. Jesus did not concern Himself about Pharisaic practice, but He was concerned to defend His own disciples without disparagement of John, and also to prevent John's way and the respect in which he was justly held from creating a prejudice against Himself. The double application of the principle was therefore present to His mind.