Exodus 6:28 – 7:7 NASB
28 Now it came about on the day when the Lord spoke to Moses in the land of Egypt, 29 that the Lord spoke to Moses, saying, “I am the Lord; speak to Pharaoh king of Egypt all that I speak to you.” 30 But Moses said before the Lord, “Behold, I am unskilled in speech; how then will Pharaoh listen to me?”
1 Then the Lord said to Moses, “See, I make you as God to Pharaoh, and your brother Aaron shall be your prophet. 2 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. 3 But I will harden Pharaoh’s heart that I may multiply My signs and My wonders in the land of Egypt.4 When Pharaoh does not listen to you, then I will lay My hand on Egypt and bring out My hosts, My people the sons of Israel, from the land of Egypt by great judgments.
5 The Egyptians shall know that I am the Lord, when I stretch out My hand on Egypt and bring out the sons of Israel from their midst.” 6 So Moses and Aaron did it; as the Lord commanded them, thus they did. 7 Moses was eighty years old and Aaron eighty-three, when they spoke to Pharaoh.