Exodus 6:29-7:7

29 he said, “I am Adonai. Tell Pharaoh, king of Egypt, everything I say to you.”

30 Moshe answered Adonai, “Look, I’m such a poor speaker that Pharaoh won’t listen to me.”

7 But Adonai said to Moshe, “I have put you in the place of God to Pharaoh, and Aharon your brother will be your prophet. 

2 You are to say everything I order you, and Aharon your brother is to speak to Pharaoh and tell him to let the people of Isra’el leave his land. 

3 But I will make him hardhearted. Even though I will increase my signs and wonders in the land of Egypt, 

4 Pharaoh will not listen to you. Then I will lay my hand on Egypt and bring my armies, my people the sons of Isra’el, out of the land of Egypt with great acts of judgment.

5 Then, when I stretch out my hand over Egypt and bring the people of Isra’el out from among them, the Egyptians will know that I am Adonai.”

6 Moshe and Aharon did exactly what Adonai ordered them to do. 

7 Moshe was eighty years old and Aharon eighty-three when they spoke to Pharaoh.