Exodus 6:10-13

10And Yhwh spake unto Moses, saying,

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

12And Moses spake before Yhwh, saying, Behold, the children of Israel have not hearkened unto me; how then shall Pharaoh hear me, who am of uncircumcised lips?

13And Yhwh spake unto Moses and unto Aaron, and gave them a charge unto the children of Israel, and unto Pharaoh king of Egypt, to bring the children of Israel out of the land of Egypt.