Albert Barnes Commentary Matthew 9:16

"And no man putteth a piece of undressed cloth upon an old garment; for that which should fill it up taketh from the garment, and a worse rent is made." — Matthew 9:16 (ASV)

No man putteth a piece of new cloth, etc. A second illustration was drawn from a well-known fact, showing also that there was a propriety or fitness of things. None of you, he says, in mending an old garment, would take a piece of entirely new cloth.

That would be a waste. An old piece, or a piece like the garment, would be better. The word here translated as new, in the original means rude, undressed, or not fulled or cleansed by the cloth-dresser. In this state, if applied to an old garment and if wet, it would contract and pull away a part of the garment to which it was attached, and thus make the rent worse than it was.

So, he says, my new doctrines do not match with the old rites of the Pharisees. There is a fitness of things. Their doctrines required much fasting. In my system it would be incongruous; and if my new doctrines were to be attached to their old ones, it would only make the matter worse.