Numbers 15

Wherefore then was he punished that was gathering the sticks? Because if the laws were to be despised even at the beginning, of course they would scarcely be observed afterwards. For indeed the Sabbath did at the first confer many and great benefits; for instance, it made them gentle towards those of their household, and humane; it taught them God's providence and the creation, as Ezekiel saith; it trained them by degrees to abstain from wickedness, and disposed them to regard the things of the Spirit.

The Law, if it lay hold on a murderer, putteth him to death; the Gospel, if it lay hold on a murderer, enlighteneth, and giveth him life. And why do I instance a murderer? The Law laid hold on one that gathered sticks on a sabbath day, and stoned him. This is the meaning of, "the letter killeth." The Gospel takes hold on thousands of homicides and robbers, and baptizing delivereth them from their former vices.