Exodus 7:2-5

You shall speak all that I command you, and your brother Aaron shall tell Pharaoh to let the children of Israel go out of his land. And I will make Pharaoh’s heart hard, and multiply My signs and My wonders (miracles) in the land of Egypt. But Pharaoh will not listen to you, and I shall lay My hand on Egypt and bring out My hosts [like a defensive army, tribe by tribe], My people the children of Israel, out of the land of Egypt by great acts of judgment (the plagues). The Egyptians shall know that I am the LORD, when I stretch out My hand on Egypt and bring out the children of Israel from among them.”