No one sews a patch of unshrunk cloth on an old garment. If he does, the new piece will pull away from the old, and a worse tear will result.
KJV
No man also seweth a piece of new cloth on an old garment: else the new piece that filled it up taketh away from the old, and the rent is made worse.
ASV
No man seweth a piece of undressed cloth on an old garment: else that which should fill it up taketh from it, the new from the old, and a worse rent is made.