Exodus 9:33-35

New Revised Standard Version, Anglicised

³³ So Moses left Pharaoh, went out of the city, and stretched out his hands to the Lord; then the thunder and the hail ceased, and the rain no longer poured down on the earth. 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.