Gerhard and Walther

For by the observance of the Sabbath, the Israelites were reminded that their sanctification is not a work of human powers; rather, it is a work of grace by God the Lord where they refrain from their activity so that God may do His work in them.—Johann Gerhard, Schola Pietatis III:393.

No one can be helped when the Gospel is made into a new law or the Law is mixed with the preaching of the Gospel.—C. F. W. Walther, God Grant It!, p. 695.