Exodus 7:3-6

But I will harden Pharaoh’s heart that I may multiply My signs and My wonders in the land of Egypt. When Pharaoh does not listen to you, then I will lay My hand on Egypt and bring out My hosts, My people the sons of Israel, from the land of Egypt by great judgments. The Egyptians shall know that I am the LORD, when I stretch out My hand on Egypt and bring out the sons of Israel from their midst.” So Moses and Aaron did it; as the LORD commanded them, thus they did.