Exodus 9:12

12 But the Lord hardened the heart of Pharaoh, and he would not listen to them, just as the Lord had spoken to Moses.

Exodus 9:12 In-Context

10 So they took soot from the kiln, and stood before Pharaoh, and Moses threw it in the air, and it caused festering boils on humans and animals.
11 The magicians could not stand before Moses because of the boils, for the boils afflicted the magicians as well as all the Egyptians.
12 But the Lord hardened the heart of Pharaoh, and he would not listen to them, just as the Lord had spoken to Moses.
13 Then the Lord said to Moses, "Rise up early in the morning and present yourself before Pharaoh, and say to him, "Thus says the Lord, the God of the Hebrews: Let my people go, so that they may worship me.
14 For this time I will send all my plagues upon you yourself, and upon your officials, and upon your people, so that you may know that there is no one like me in all the earth.
New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.