I am sure you could provide me with a wonderful treatise on the covenants. You will no doubt provide intricate and intimate details of the difference between old and new, describing all the nuances that exist affecting obedience, grace, salvation, and works. But there is one thing, despite all the wisdom you may bring with your erudite prose, that will be missing.
That one thing no scholar, no biblical theologian, no professor of linguistics or doctor of divinity could provide. An authoritative conclusive statement stating clearly and succinctly that the keeping holy of the Sabbath is no longer a commandment. No-one since the apostles put pen to paper has ever produced one. Nor I am sure, will you. No disrespect toward you, I am sure you know your Bible very well and could offer an excellent written submission on why the Sabbath ought no longer be observed... But it will lack one integral ingredient that if produced, will convince me. Divine authority.