Exodus 6:6

6:6 Therefore, tell the Israelites, ‘I am the Lord. I will bring you out from your enslavement to the Egyptians, I will rescue you from the hard labor they impose, and I will redeem you with an outstretched arm and with great judgments.

Exodus 13:15

13:15 When Pharaoh stubbornly refused to release us, the Lord killed all the firstborn in the land of Egypt, from the firstborn of people to the firstborn of animals. That is why I am sacrificing to the Lord the first male offspring of every womb, but all my firstborn sons I redeem.’