Exodus 9:27-30

Then Pharaoh sent for Moses and Aaron, and said to them, “I have sinned this time; the LORD is righteous, and I and my people are wicked. Pray and entreat the LORD, for there has been enough of God’s thunder and hail; I will let you go, and you shall stay here no longer.” Moses said to him, “As soon as I leave the city, I will stretch out my hands to the LORD; the thunder will cease and there will be no more hail, so that you may know [without any doubt] and acknowledge that the earth is the LORD’S. But as for you and your servants, I know that you do not yet fear the LORD God.”