Romans 9:18

So, then, He hath mercy on whom He willeth, and whom He willeth He hardeneth.

John 12:40

"He hath blinded their eyes, and He hardened their heart, lest they should see with their eyes, and understand with their heart, and turn, and I should heal them."

Romans 1:28

And, as they did not approve the holding of God in their knowledge, God delivered them up to a reprobate mind, to do those things which are not becoming;

Romans 11:8-10

as it has been written, "God gave them a spirit of stupor, eyes that they should not see, and ears that they should not hear, unto this day."

2 Corinthians 2:16

to the one class a savor of death unto death, and to the other a savor of life unto life. And who is sufficient for these things?

2 Thessalonians 2:10-12

and in all deceit of unrighteousness to those who perish; because they received not the love of the truth, that they might be saved.

1 Peter 2:8

and "a stone of stumbling, and rock of offense"; who stumble, being disobedient to the word, to which also they were appointed.

Treasury of Scripture Knowledge

Summary

And the LORD said unto Moses, When thou goest to return into Egypt, see that thou do all those wonders before Pharaoh, which I have put in thine hand: but I will harden his heart, that he shall not let the people go.

Bible References

I will harden

John 12:40
"He hath blinded their eyes, and He hardened their heart, lest they should see with their eyes, and understand with their heart, and turn, and I should heal them."
Romans 1:28
And, as they did not approve the holding of God in their knowledge, God delivered them up to a reprobate mind, to do those things which are not becoming;
Romans 9:18
So, then, He hath mercy on whom He willeth, and whom He willeth He hardeneth.
Romans 11:8
as it has been written, "God gave them a spirit of stupor, eyes that they should not see, and ears that they should not hear, unto this day."
2 Corinthians 2:16
to the one class a savor of death unto death, and to the other a savor of life unto life. And who is sufficient for these things?
2 Thessalonians 2:10
and in all deceit of unrighteousness to those who perish; because they received not the love of the truth, that they might be saved.
1 Peter 2:8
and "a stone of stumbling, and rock of offense"; who stumble, being disobedient to the word, to which also they were appointed.