Roman Catechism 23.8

Chapter 23 — Part III: The Decalogue — Introduction on the Commandments in General

Section 8. The reflection that God is the author of the law is highly useful, and exercises great influence in persuading (to its observance); for we cannot doubt His wisdom and justice, nor can we escape His infinite power and might. Hence, when by His Prophets He commands the law to be observed, He proclaims that He is the Lord God; and the Decalogue itself opens: I am the Lord thy God; and elsewhere (we read): If I am a master, where is my fear?