Exodus 5:1-2

Darby Translation

5 And afterwards Moses and Aaron went in, and said to Pharaoh, Thus saith Jehovah, the God of Israel, Let my people go that they may celebrate a feast to me in the wilderness.

² And Pharaoh said, Who is Jehovah, to whose voice I am to hearken to let Israel go? I do not know Jehovah, neither will I let Israel go.