Exodus 8:15, 19, 32

But when Pharaoh saw that there was a respite, he hardened his heart and would not listen to them, as the LORD had said.

Then the magicians said to Pharaoh, “This is the finger of God.” But Pharaoh’s heart was hardened, and he would not listen to them, as the LORD had said.

But Pharaoh hardened his heart this time also, and did not let the people go.