Exodus 9:7

And Pharaoh sent [to check], and {it turned out} not even one from the livestock of Israel had died, but Pharaoh's heart was {insensitive}, and he did not release the people.

Exodus 7:14

And Yahweh said to Moses, "Pharaoh's heart [is] {insensitive}; he refuses to release the people.

Exodus 8:32

And Pharaoh made his heart {insensitive} also this time, and he did not release the people.

Exodus 9:12

And Yahweh hardened Pharaoh's heart, and he did not listen to them, as Yahweh had spoken to Moses.

Job 9:4

[He is] wise in heart and mighty in strength; who has resisted him and succeeded?

Proverbs 29:1

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

Isaiah 48:4

because {I know} that you [are] obstinate, and your neck an iron sinew, and your forehead bronze.

Daniel 5:20

But {when} his heart became arrogant and his spirit became hard [so as] to act proudly, he was deposed from the throne of his kingdom and the glory {was taken away from him}.

Romans 9:18

Consequently therefore, he has mercy on whomever he wishes, and he hardens whomever he wishes.

Treasury of Scripture Knowledge

Summary

And Pharaoh sent, and, behold, there was not one of the cattle of the Israelites dead. And the heart of Pharaoh was hardened, and he did not let the people go.

Bible References

The heart

Exodus 9:12
And Yahweh hardened Pharaoh's heart, and he did not listen to them, as Yahweh had spoken to Moses.
Exodus 7:14
And Yahweh said to Moses, "Pharaoh's heart [is] {insensitive}; he refuses to release the people.
Exodus 8:32
And Pharaoh made his heart {insensitive} also this time, and he did not release the people.
Job 9:4
[He is] wise in heart and mighty in strength; who has resisted him and succeeded?
Proverbs 29:1
A man who is reproved, being stubborn of neck-- suddenly he will be broken, and there will not be healing.
Isaiah 48:4
because {I know} that you [are] obstinate, and your neck an iron sinew, and your forehead bronze.
Daniel 5:20
But {when} his heart became arrogant and his spirit became hard [so as] to act proudly, he was deposed from the throne of his kingdom and the glory {was taken away from him}.
Romans 9:18
Consequently therefore, he has mercy on whomever he wishes, and he hardens whomever he wishes.