Then the Lord said to Moses, "Now you shall see what I will do to Pharaoh: Indeed, by a mighty hand he will let them go; by a mighty hand he will drive them out of his land."
God also spoke to Moses and said to him: "I am the Lord.
I appeared to Abraham, Isaac, and Jacob as God Almighty, but by my name "The Lord' I did not make myself known to them.
References for Exodus 6:3
I also established my covenant with them, to give them the land of Canaan, the land in which they resided as aliens.
I have also heard the groaning of the Israelites whom the Egyptians are holding as slaves, and I have remembered my covenant.
Say therefore to the Israelites, "I am the Lord, and I will free you from the burdens of the Egyptians and deliver you from slavery to them. I will redeem you with an outstretched arm and with mighty acts of judgment.
I will take you as my people, and I will be your God. You shall know that I am the Lord your God, who has freed you from the burdens of the Egyptians.
I will bring you into the land that I swore to give to Abraham, Isaac, and Jacob; I will give it to you for a possession. I am the Lord.' "
Moses told this to the Israelites; but they would not listen to Moses, because of their broken spirit and their cruel slavery.
Then the Lord spoke to Moses,
"Go and tell Pharaoh king of Egypt to let the Israelites go out of his land."