Exodus 9:27-35

Then Pharaoh quickly summoned Moses and Aaron. “This time I have sinned,” he confessed. “The LORD is the righteous one, and my people and I are wrong. Please beg the LORD to end this terrifying thunder and hail. We’ve had enough. I will let you go; you don’t need to stay any longer.” “All right,” Moses replied. “As soon as I leave the city, I will lift my hands and pray to the LORD. Then the thunder and hail will stop, and you will know that the earth belongs to the LORD. But I know that you and your officials still do not fear the LORD God.” (All the flax and barley were ruined by the hail, because the barley had formed heads and the flax was budding. But the wheat and the emmer wheat were spared, because they had not yet sprouted from the ground.) So Moses left Pharaoh’s court and went out of the city. When he lifted his hands to the LORD, the thunder and hail stopped, and the downpour ceased. But when Pharaoh saw that the rain, hail, and thunder had stopped, he and his officials sinned again, and Pharaoh again became stubborn. Because his heart was hard, Pharaoh refused to let the people leave, just as the LORD had predicted through Moses.