Exodus 8:15

And Pharaoh saw that there was relief, and he made his heart {insensitive}, and he did not listen to them, as Yahweh had spoken.

Exodus 7:4

And Pharaoh will not listen to you, and I will put my hand into Egypt and bring out my divisions, my people, the {Israelites}, from the land of Egypt with great punishments.

Ecclesiastes 8:11

Because sentence against an evil deed is not carried out quickly, the heart of {humans} fills up within them to do evil.

Exodus 4:21

And Yahweh said to Moses, "When you go to return to Egypt, see all of the wonders that I have put in your hand, and do them before Pharaoh, and I myself will harden his heart, and he will not release the people.

Exodus 7:13-14

And Pharaoh's heart was hard, and he did not listen to them, as Yahweh had said.

Exodus 14:5

And it was told to the king of Egypt that the people fled, and the heart of Pharaoh was changed and [that of] his servants toward the people, and they said, "What [is] this we have done, that we have released Israel from serving us!"

Proverbs 29:1

A man who is reproved, being stubborn of neck-- suddenly he will be broken, and there will not be healing.

Isaiah 26:10

[Though the] wicked person is shown compassion, he does not learn righteousness; he acts unjustly in [the] land [of] uprightness, and he does not see the majesty of Yahweh.

Jeremiah 34:7-11

when the army of the king of Babylon [was] fighting against Jerusalem and against all the cities of Judah that were left over--Lachish and Azekah, for these remained among the cities of Judah, the cities of fortification.

Hosea 6:4

What will I do with you, Ephraim? What will I do with you, Judah? Your love [is] like a morning cloud, like the dew that goes away early in the morning.

Zechariah 7:11-12

But they refused to listen, and turned a stubborn shoulder and {stopped their ears from listening}.

Hebrews 3:8

do not harden your hearts as in the rebellion, in the day of testing in the wilderness,

Hebrews 3:15

{while it is said}, "Today, if you hear his voice, do not harden your hearts as in the rebellion."

Revelation 16:9

And people were burned up [by the] great heat, and they blasphemed the name of God who has the authority over these plagues, and they did not repent to give him glory.

Treasury of Scripture Knowledge

Summary

But when Pharaoh saw that there was respite, he hardened his heart, and hearkened not unto them; as the LORD had said.

Bible References

He hardened

Exodus 4:21
And Yahweh said to Moses, "When you go to return to Egypt, see all of the wonders that I have put in your hand, and do them before Pharaoh, and I myself will harden his heart, and he will not release the people.
Exodus 7:4
And Pharaoh will not listen to you, and I will put my hand into Egypt and bring out my divisions, my people, the {Israelites}, from the land of Egypt with great punishments.
Proverbs 29:1
A man who is reproved, being stubborn of neck-- suddenly he will be broken, and there will not be healing.
Zechariah 7:11
But they refused to listen, and turned a stubborn shoulder and {stopped their ears from listening}.
Hebrews 3:8
do not harden your hearts as in the rebellion, in the day of testing in the wilderness,
Revelation 16:9
And people were burned up [by the] great heat, and they blasphemed the name of God who has the authority over these plagues, and they did not repent to give him glory.

General references

Exodus 7:13
And Pharaoh's heart was hard, and he did not listen to them, as Yahweh had said.
Exodus 8:32
And Pharaoh made his heart {insensitive} also this time, and he did not release the people.
Jeremiah 34:11
But {afterward} they turned back and they brought back the [male] slaves and the female slaves whom they had let go free, and they subdued them as [male] slaves and female slaves.