Calvin's Commentaries, Vol. 3: Harmony of the Law, Part I, tr. by John King, [1847-50], at sacred-texts.com
1. And God spoke all these words, saying,
1. Et loquutus est Deus omnia verba haec: dicendo,
2. I am the Lord thy God, which have brought thee out of the land of Egypt, out of the house of bondage.
2. Ego Jehova Deus tuus, qui eduxi te e terra AEgypti, e domo servorum.
1. And God spoke. I am aware that many agree in reading this verse and the next in connection with each other, and thus making them together the first of the ten commandments. Others taking them separately, consider the affirmation to stand in the place of one entire commandment; but since God neither forbids nor commands anything here, but only comes forth before them in His dignity, to devote the people to Himself, and to claim the authority He deserves, which also He would have extended to the whole Law, I make no doubt but that it is a general preface, whereby He prepares their minds for obedience. And surely it was necessary that, first of all, the right of the legislator should be established, lest what He chose to command should be despised, or contemptuously received. In these words, then, God seeks to procure reverence to Himself, before He prescribes the rule of a holy and righteous life. Moreover, He not merely declares Himself to be Jehovah, the only God to whom men are bound by the right of creation, who has given them their existence, and who preserves their life, nay, who is Himself the life of all; but He adds, that He is the peculiar God of the Israelites; for it was expedient, not only that the people should be alarmed by the majesty of God, but also that they should be gently attracted, so that the law might be more precious than gold and silver, and at the same time “sweeter than honey,” (Ps. 119:72, 103;) for it would not be enough for men to be compelled by servile fear to bear its yoke, unless they were also attracted by its sweetness, and willingly endured it. He afterwards recounts that special blessing, wherewith He had honored the people, and by which He had testified that they were not elected by Him in vain; for their redemption was the sure pledge of their adoption. But, in order to bind them the better to Himself, He reminds them also of their former condition; for Egypt was like a house of bondage, from whence the Israelites were delivered. Wherefore, they were no more their own masters, since God had purchased them unto Himself. This does not indeed literally apply to us; but He has bound us to Himself with a holier tie, by the hand of His only-be-gotten Son; whom Paul teaches to have died, and risen again, “that He might be Lord both of the dead and the living.” (Ro 14:9.) So that He is not now the God of one people only, but of all nations, whom He has called into His Church by general adoption.