Deuteronomy 5:30

30.Go say to them. He more plainly subjoins God’s consent to the people’s prayer; as much as to say, that what they had asked was ratified by God’s decree; whence it follows that, if they refuse to obey Moses, they will not be only guilty of perverseness and levity, but will violate a divine decree. I have before shown why God honors the doctrines of the law by various titles, viz., that the Israelites may more willingly acquiesce in them. But, lest they should think that what was enjoined them was only to remain in force, and to be observed for a short time, He expressly refers to the perpetuity of the Law; for this is the import of the words, in which He declares Himself to teach them what they were to do in the land which He should give them.