Exodus 6:10-13

10And Jehovah spoke to Moses, saying,

11Go in, speak unto Pharaoh king of Egypt, that he let the children of Israel go out of his land.

12And Moses spoke before Jehovah, saying, Lo, the children of Israel do not hearken to me: how then should Pharaoh hearken to me, to me of uncircumcised lips?

13And Jehovah spoke to Moses and to Aaron, and gave them a commandment to the children of Israel, and to Pharaoh king of Egypt, to bring the children of Israel out of the land of Egypt.