Adam Clarke on Ezekiel 20:12

I gave them my Sabbaths - The religious observance of the Sabbath was the first statute or command of God to men. This institution was a sign between God and them, to keep them in remembrance of the creation of the world, of the rest that he designed them in Canaan, and of the eternal inheritance among the saints in light. Of these things the Sabbath was a type and pledge.