Exodus 9:12, 35
Exodus 9:12 AMP
But the LORD hardened the heart of Pharaoh, and he did not listen or pay attention to them, just as the LORD had told Moses.
Exodus 9:35 AMP
Pharaoh’s heart was hardened, and he did not let the Israelites go, just as the LORD had said through Moses. [Ex 4:21]