Exodus 6:10-13

10So Adonai told Moses,

11“Go, speak to Pharaoh king of Egypt, so that will he let Bnei-Yisrael go out of his land.”

12But Moses said to Adonai, “Bnei-Yisrael have not listened to me. So how would Pharaoh listen to me—I, who have uncircumcised lips?”

13Then Adonai spoke to Moses and to Aaron and gave to them a charge for Bnei-Yisrael and Pharaoh king of Egypt, to bring Bnei-Yisrael out of the land of Egypt.