Romans 9:18

Therefore, he has mercy on whom he wills to have mercy: and whom he wills to harden, he hardens.

John 12:40

He has blinded their eyes, and hardened their heart, lest they should see with their eyes, and understand with their heart, and should turn, and I should give them health.

Romans 1:28

And as they refused to acknowledge God, God delivered them up to an undiscerning mind, to do detestable things;

Romans 11:8-10

as it is written: God has given them a spirit of stupor, eyes with which they can not see, and ears with which they can not hear.

2 Corinthians 2:16

to the one, we are the odor of death ending in death; to the other, the odor of life ending in life: and who is sufficient for these things?

2 Thessalonians 2:10-12

and with all the delusion of unrighteousness in those who perish, because they did not receive the love of the truth, in order that they might be saved.

1 Peter 2:8

and a stone of stumbling, and a rock of offense to the disobedient, who stumble at the word because they are disobedient, to which stumbling they were also 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 has blinded their eyes, and hardened their heart, lest they should see with their eyes, and understand with their heart, and should turn, and I should give them health.
Romans 1:28
And as they refused to acknowledge God, God delivered them up to an undiscerning mind, to do detestable things;
Romans 9:18
Therefore, he has mercy on whom he wills to have mercy: and whom he wills to harden, he hardens.
Romans 11:8
as it is written: God has given them a spirit of stupor, eyes with which they can not see, and ears with which they can not hear.
2 Corinthians 2:16
to the one, we are the odor of death ending in death; to the other, the odor of life ending in life: and who is sufficient for these things?
2 Thessalonians 2:10
and with all the delusion of unrighteousness in those who perish, because they did not receive the love of the truth, in order that they might be saved.
1 Peter 2:8
and a stone of stumbling, and a rock of offense to the disobedient, who stumble at the word because they are disobedient, to which stumbling they were also appointed.