Exodus 7:4-8

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.

And Moses was eighty years old and Aaron eighty-three, when they spoke to Pharaoh. Aaron’s Staff Turns into a Serpent

Now the Lord spoke to Moses and Aaron, saying,