Exodus 6:10-12

10Then the LORD said to Moses,

11“Go, tell Pharaoh king of Egypt to let the Israelites go out of his country.”

12But Moses said to the LORD, “If the Israelites will not listen to me, why would Pharaoh listen to me, since I speak with faltering lips Hebrew I am uncircumcised of lips; also in verse 30 ?”