Q. 100 What is the Preface to the ten Commandments?
A. I am JEHOVAH, the Lord your God, who brought you out of the Land of Egypt, out of the House of Bondage.

Q. 101 What do we learn from the Preface?
A. Three things: first he shows to whom the right of all Rule belongs, that is, to God himself for he says, “I am JEHOVAH”. Secondly, he says he is the God of his people, that through the promise of his bountifulness he might encourage them to obey him. Thirdly, he says, who brought you out of the land of Egypt, as if he should say, I am the one who made myself known to you and bestowed all those Blessings upon you; therefore you art bound to show thankfulness and obedience unto me.
Exod. 20.2.

Q. 102 Do these things belong to us?
A. Yes, because they figuratively include and imply all the deliverances of the Church; and further, also this was a type of our wonderful Deliverance achieved by Christ.