The Mosaic Covenant is eternal (Exodus 33:14-17, Leviticus 24:8), so its terms are included in the New Covenant (Jeremiah 31:33, Hebrews 8:10). In Galatians 3:16-19, a newer covenant does not nullify the promises of a covenant that has already been ratified, so it does not nullify our need to obey God's law in connection with the promise.the old covenant is done away with. no one is to observe the old covenant.
Moreover, a day that is holy is set apart and in order for something to be set apart there needs to be something else that it is set apart from, so to treat every day the same is to treat none of them as holy. In theory, God could have commanded to keep every day holy if that wasn't contradictory, but in His wisdom He commanded to keep the 7th day holy, so we should not think that we know better than God. If we did on every day what God wants us to do on the Sabbath, then we would do no work, but God also wants us to work.as for the sabbath, is not every day the sabbath? one should be at "REST" in Christ Jesus. for in the Lord Jesus, we have REST.
are we not in the seventh day "REST" in God? for do not the believer LIVES in God, and not of himself? and is not God at REST? when one gives his, or her life to Christ, it is no longer he who lives but Christ who lives in US.
In 1 John 2:6, those who are in Christ are obligated to walk in the same way he walked, so walking in obedience to His law is the find way to rest in Christ. In Matthew 11:28-30, Jesus invited people to come to him and to learn from him, not inviting people to reject his example of walking in obedience to God's law. By saying that we would find rest for our souls, he was referencing Jeremiah 6:16-19, where God's law is described as the good way where we will find rest for our souls.
In Hebrews 3:18-19, they did not enter into God's rest because of their disobedience/unbelief, and in Ezekiel 20:13, it specifically mentions that they greatly profaned God's Sabbaths. In Hebrews 4:9-11, there remains a Sabbath rest for the people of God, we should rest from our work as God rest from his, and we should strive to enter into that rest so that no one may fall away by the same sort of disobedience, so entering into God's rest should not be used to justify the same sort of disobedience. Christ lived in obedience to God's law, including keeping the 7th day holy, so that is the way that we live when he is living in us.