Exodus 6:26-30

These are the Aaron and Moses to whom the LORD said: “Bring out the people of Israel from the land of Egypt by their hosts.” It was they who spoke to Pharaoh king of Egypt about bringing out the people of Israel from Egypt, this Moses and this Aaron. On the day when the LORD spoke to Moses in the land of Egypt, the LORD said to Moses, “I am the LORD; tell Pharaoh king of Egypt all that I say to you.” But Moses said to the LORD, “Behold, I am of uncircumcised lips. How will Pharaoh listen to me?”