Exodus 5:1-2

American Standard Version

5 And afterward Moses and Aaron came, and said unto Pharaoh, Thus saith Jehovah, the God of Israel, Let my people go, that they may hold a feast unto me in the wilderness. ² And Pharaoh said, Who is Jehovah, that I should hearken unto his voice to let Israel go? I know not Jehovah, and moreover I will not let Israel go.