Exodus 9:7, 12, 34-35

Pharaoh sent his officials to investigate, and they discovered that the Israelites had not lost a single animal! But even so, Pharaoh’s heart remained stubborn, and he still refused to let the people go.

But the LORD hardened Pharaoh’s heart, and just as the LORD had predicted to Moses, Pharaoh refused to listen.

But when Pharaoh saw that the rain, hail, and thunder had stopped, he and his officials sinned again, and Pharaoh again became stubborn. Because his heart was hard, Pharaoh refused to let the people leave, just as the LORD had predicted through Moses.