Exodus 11:9-10

American Standard Version

⁹ And Jehovah said unto Moses, Pharaoh will not hearken unto you; that my wonders may be multiplied in the land of Egypt. ¹⁰ And Moses and Aaron did all these wonders before Pharaoh: and Jehovah ^[a]hardened Pharaoh’s heart, and he did not let the children of Israel go out of his land.