As with the Sabbath, work symbolizes our own effort, and our own effort will always fall short of what God demands for salvation. Anything that resembled work was inappropriate in the house of God.
What are "works of the law?" Any rule, command or law that a person observes in an attempt to be accepted in right standing with God is a "work of the law." In other words, "works of the law" are a righteousness produced by one's self, a righteousness belonging to one's self, offered to God as a means of meeting God's standard for acceptance.
It takes a revelation of the gospel of grace to abandon faith in the works of the law. God's standard of righteousness is the RIGHTEOUSNESS OF GOD alone. God has designed salvation in such a way as to eliminate any boasting from man. If salvation was by works either partially or wholly, then man could boast.
But grace and faith eliminate man's boasting. Faith towards God and what He has done through Christ Jesus is the only means of receiving His free gift of salvation. Salvation by grace brings praise and glory to God. If we could save ourselves, either partially or wholly, we would take the credit for it. But that is not the case.
All the glory goes to God.