“I am the Lord your God, who brought you out of Egypt, out of the land of slavery.”
The Ten Commandments begin with a reminder of the relationship history between YHWH and Israel. At this point in the story, God had just brought them out of Egypt and they had not yet taken possession of the Promised Land, so the history is short. Yet, one thing is certain: He is their God. He belongs to Israel and Israel belongs to him.
This exclusivity is essential to their relationship. He is their only God, the only deity who brought them out of Egypt. He did not cooperate with, or rely upon, any other gods to perform these miracles, and therefore he has an exclusive claim upon the lives of the Israelites. But he is also, at the time the Ten Commandments were given, only the God of Israel. He is not yet the God of Egypt, Canaan, or any other land. The Exodus event is the moment that YHWH appeared on the scene, so he was not yet known among the nations. The Israelites are his only people, the only nation that has even heard of YHWH. This exclusivity creates a sense of intimacy between God and Israel, and this intimate relationship is the foundation upon which the Ten Commandments are built.