I am the LORD thy God, which have brought thee out of the land of Egypt, out of the house of bondage.

Wesley's Notes

20:2 I am the Lord thy God - Herein, God asserts his own authority to enact this law; and proposeth himself as the sole object of that religious worship which is enjoined in the four first commandments. They are here bound to obedience. Because God is the Lord, Jehovah, self - existent, independent, eternal, and the fountain of all being and power; therefore he has an incontestable right to command us. He was their God; a God in covenant with them; their God by their own consent. He had brought them out of the land of Egypt - Therefore they were bound in gratitude to obey him, because he had brought them out of a grievous slavery into a glorious liberty. By redeeming them, he acquired a farther right to rule them; they owed their service to him, to whom they owed their freedom. And thus, Christ, having rescued us out of the bondage of sin, is entitled to the best service we can do him. The four first commandments, concern our duty to God (commonly called the first - table.) It was fit those should be put first, because man had a Maker to love before he had a neighbour to love, and justice and charity are then only acceptable to God when they flow from the principles of piety.

King James Translators' Notes

bondage: Heb. servants

Jamieson-Fausset-Brown Bible Commentary

2. I am the Lord thy God-This is a preface to the ten commandments-the latter clause being specially applicable to the case of the Israelites, while the former brings it home to all mankind; showing that the reasonableness of the law is founded in their eternal relation as creatures to their Creator, and their mutual relations to each other.

Matthew Henry's Concise Commentary

20:1,2 God speaks many ways to the children of men; by conscience, by providences, by his voice, to all which we ought carefully to attend; but he never spake at any time so as he spake the TEN COMMANDMENTS. This law God had given to man before; it was written in his heart; but sin so defaced it, that it was necessary to revive the knowledge of it. The law is spiritual, and takes knowledge of the secret thoughts, desires, and dispositions of the heart. Its grand demand is love, without which outward obedience is mere hypocrisy. It requires perfect, unfailing, constant obedience; no law in the world admits disobedience to itself. Whosoever shall keep the whole law, and yet offend in one point, he is guilty of all, Jas 2:10. Whether in the heart or the conduct, in thought, word, or deed, to omit or to vary any thing, is sin, and the wages of sin is death.