Exodus 7:1-7

Then the LORD said to Moses, “Pay close attention to this. I will make you seem like God to Pharaoh, and your brother, Aaron, will be your prophet. Tell Aaron everything I command you, and Aaron must command Pharaoh to let the people of Israel leave his country. But I will make Pharaoh’s heart stubborn so I can multiply my miraculous signs and wonders in the land of Egypt. Even then Pharaoh will refuse to listen to you. So I will bring down my fist on Egypt. Then I will rescue my forces—my people, the Israelites—from the land of Egypt with great acts of judgment. When I raise my powerful hand and bring out the Israelites, the Egyptians will know that I am the LORD.” So Moses and Aaron did just as the LORD had commanded them. Moses was eighty years old, and Aaron was eighty-three when they made their demands to Pharaoh.