Perhaps just the deep study of Romans 1:5 will help:
Romans 1:5 “By whom we have received grace…for obedience…to the faith, among all nations, for his name”.
As Ephesians 2:8 says….Grace, is the gift of God (salvation is not a gift).
Grace (God’s power to obey)….leads one, to do what God says to do, to obtain the results of Salvation.
So, when God requires the Christian, to keep the 4th commandment, the 7th day Sabbath….it requires grace …from God, to do it.