Exodus 4:21

4:21 The Lord said to Moses, “When you go back to Egypt, see that you do before Pharaoh all the wonders I have put under your control. But I will harden his heart and he will not let the people go.

Exodus 7:4

7:4 Pharaoh will not listen to you. I will reach into Egypt and bring out my regiments, my people the Israelites, from the land of Egypt with great acts of judgment.

Exodus 7:13-14

7:13 Yet Pharaoh’s heart became hard, and he did not listen to them, just as the Lord had predicted.

The First Blow: Water to Blood

7:14 The Lord said to Moses, “Pharaoh’s heart is hard; he refuses to release the people.

Proverbs 29:1

29:1 The one who stiffens his neck after numerous rebukes

will suddenly be destroyed without remedy.

Zechariah 7:11-12

7:11 “But they refused to pay attention, turning away stubbornly and stopping their ears so they could not hear. 7:12 Indeed, they made their heart as hard as diamond, so that they could not obey the Torah and the other words the Lord who rules over all had sent by his Spirit through the former prophets. Therefore, the Lord who rules over all had poured out great wrath.

Hebrews 3:8

3:8 “Do not harden your hearts as in the rebellion, in the day of testing in the wilderness.

Hebrews 3:15

3:15 As it says, “Oh, that today you would listen as he speaks! Do not harden your hearts as in the rebellion.”

Revelation 16:9

16:9 Thus people were scorched by the terrible heat, yet they blasphemed the name of God, who has ruling authority over these plagues, and they would not repent and give him glory.