Exodus 9:34-35

New Revised Standard Version, Anglicised

³⁴ But when Pharaoh saw that the rain and the hail and the thunder had ceased, he sinned once more and hardened his heart, he and his officials. ³⁵ So the heart of Pharaoh was hardened, and he would not let the Israelites go, just as the Lord had spoken through Moses.