Romans 9:18

Well then, he hath mercy on whom he will, but whom he will he hardeneth.

John 12:40

"He hath blinded their eyes, and hardened their hearts; lest they should see with their eyes, and understand with the heart, and be converted, and I should heal them."

Romans 1:28

And since they thought not fit to hold the Deity in acknowledgment, God abandoned them to a reprobate mind, to practise deeds unbecoming;

Romans 11:8-10

as it is written, "God hath given them the spirit of slumber, eyes that they should not see, and ears that they should not hear; unto this present day."

2 Corinthians 2:16

To the one we are the odour of death unto death, to the other the odour of life unto life: and who is sufficient for these things?

2 Thessalonians 2:10-12

and in every unrighteous delusion among those who perish: in consequence of which things 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 offence," to those who stumble at the word, disobedient; whereunto 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 hardened their hearts; lest they should see with their eyes, and understand with the heart, and be converted, and I should heal them."
Romans 1:28
And since they thought not fit to hold the Deity in acknowledgment, God abandoned them to a reprobate mind, to practise deeds unbecoming;
Romans 9:18
Well then, he hath mercy on whom he will, but whom he will he hardeneth.
Romans 11:8
as it is written, "God hath given them the spirit of slumber, eyes that they should not see, and ears that they should not hear; unto this present day."
2 Corinthians 2:16
To the one we are the odour of death unto death, to the other the odour of life unto life: and who is sufficient for these things?
2 Thessalonians 2:10
and in every unrighteous delusion among those who perish: in consequence of which things 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 offence," to those who stumble at the word, disobedient; whereunto also they were appointed.