Exodus 20:1

Here is, I. The preface of the law-writer, Moses: God spoke all these words, Exo 20:1. The law of the ten commandments is, 1. A law of God's making. They are enjoined by the infinite eternal Majesty of heaven and earth. And where the word of the King of kings is surely there is power. 2. It is a law of his own speaking. God has many ways of speaking to the children of men (Job 33:14); once, yea twice - by his Spirit, by conscience, by providences, by his voice, all which we ought carefully to attend to; but he never spoke, at any time, upon any occasion, as he spoke the ten commandments, which therefore we ought to hear with the more earnest heed. They were not only spoken audibly (so he owned the Redeemer by a voice from heaven, Mat 3:17), but with a great deal of dreadful pomp. This law God had given to man before (it was written in his heart by nature); but sin had so defaced that writing that it was necessary, in this manner, to revive the knowledge of it. II. The preface of the Law-maker: I am the Lord thy God, Exo 20:2. Herein, 1. God asserts his own authority to enact this law in general: "I am the Lord who command thee all that follows." 2. He proposes himself as the sole object of that religious worship which is enjoined in the first four of the commandments.

— Matthew Henry's Concise Commentary (public domain)