Exodus 7:2-6

As for you, you shall speak all that I command you, and your brother Aaron shall speak to Pharaoh that he let the sons of Israel go out of his land.

But I will harden Pharaoh’s heart, so that I may multiply My signs and My wonders in the land of Egypt.

When Pharaoh does not listen to you, I will lay My hand on Egypt and bring out My armies, My people the sons of Israel, from the land of Egypt by great judgments.

Then the Egyptians shall know that I am the Lord, when I extend My hand over Egypt and bring out the sons of Israel from their midst.”

So Moses and Aaron did this; as the Lord commanded them, so they did.