John Gill Bible Commentary

No man also seweth a piece of new cloth, The traditions of the elders are meant, particularly concerning eating and drinking, and fasting, things before spoken of; and which occasioned this parable, and which were new things in comparison of the commands of God: some of them were of very short standing, devised in, that age; and most, if not all of them, were since the times of Ezra. On an old garment; the moral and ceremonial righteousness of the Jews, in obedience to the law of God; signifying, that the former were not to be joined with these, to make up a justifying righteousness before God; which were not sufficient for such a purpose, either singly, or both together: else the new piece that filled it up, taketh away from the old, and the rent is made worse; for by attendance to the traditions of the elders, the Jews were taken off from, and neglected the commandments of God; nay, oftentimes the commands of God were made void by these traditions, so that the old garment of their own righteousness, which was very ragged and imperfect of itself, instead of being purer and more perfect, became much the worse, even for the purpose for which it was intended; See Gill on Mat 9:16.