Exodus 7:13, 16, 22

Pharaoh’s heart, however, remained hard. He still refused to listen, just as the LORD had predicted.

Then announce to him, ‘The LORD, the God of the Hebrews, has sent me to tell you, “Let my people go, so they can worship me in the wilderness.” Until now, you have refused to listen to him.

But again the magicians of Egypt used their magic, and they, too, turned water into blood. So Pharaoh’s heart remained hard. He refused to listen to Moses and Aaron, just as the LORD had predicted.