Exodus 9:12

And Yahweh said to Moses, “When you go to return to Egypt, see to it that all the miraculous wonders which I have put in your hand, that you do them before Pharaoh; but as for Me, I will harden his heart with strength so that he will not let the people go.

“But Pharaoh will not listen to you. And I will set My hand upon Egypt and bring out My hosts, My people the sons of Israel, from the land of Egypt by great judgments.

Yet Pharaoh’s heart was hardened with strength, and he did not listen to them, as Yahweh had spoken.

Now Moses and Aaron did all these miraculous wonders before Pharaoh; yet Yahweh hardened Pharaoh’s heart with strength, and he did not let the sons of Israel go out of his land.

“Then You performed signs and wonders against Pharaoh, Against all his servants and all the people of his land; For You knew that they acted presumptuously toward them, And made a name for Yourself as it is this day.

So then He has mercy on whom He desires, and He hardens whom He desires.