Exodus 9:12-14 Revised Standard Version (RSV)
12 But the Lord hardened the heart of Pharaoh, and he did not listen to them; as the Lord had spoken to Moses.
The Seventh Plague: Thunder and Hail
13 Then the Lord said to Moses, “Rise up early in the morning and stand before Pharaoh, and say to him, ‘Thus says the Lord, the God of the Hebrews, “Let my people go, that they may serve me. 14 For this time I will send all my plagues upon your heart, and upon your servants and your people, that you may know that there is none like me in all the earth.