Romans 9:18

So, then, where God wills, he takes pity, and where he wills, he hardens the heart.

John 12:40

'He has blinded their eyes, and blunted their mind, so that they should not see with their eyes, and perceive with their mind, and turn--And I should heal them.'

Romans 1:28

Then, as they would not keep God before their minds, God abandoned them to depraved thoughts, so that they did all kinds of shameful things.

Romans 11:8-10

The rest grew callous; as Scripture says--'God has given them a deadness of mind--eyes that are not to see and ears that are not to hear--and it is so to this very day.'

2 Corinthians 2:16

To the latter we are an odor which arises from death and tells of Death; to the former an odor which arises from life and tells of Life. But who is equal to such a task?

2 Thessalonians 2:10-12

to the ruin of those who are on the path to destruction, because they have never received and loved the Truth to their own Salvation.

1 Peter 2:8

and 'a stumbling-block, and a rock which shall prove a hindrance.' They stumble because they do not accept the Message. This was the fate destined for them.

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 blunted their mind, so that they should not see with their eyes, and perceive with their mind, and turn--And I should heal them.'
Romans 1:28
Then, as they would not keep God before their minds, God abandoned them to depraved thoughts, so that they did all kinds of shameful things.
Romans 9:18
So, then, where God wills, he takes pity, and where he wills, he hardens the heart.
Romans 11:8
The rest grew callous; as Scripture says--'God has given them a deadness of mind--eyes that are not to see and ears that are not to hear--and it is so to this very day.'
2 Corinthians 2:16
To the latter we are an odor which arises from death and tells of Death; to the former an odor which arises from life and tells of Life. But who is equal to such a task?
2 Thessalonians 2:10
to the ruin of those who are on the path to destruction, because they have never received and loved the Truth to their own Salvation.
1 Peter 2:8
and 'a stumbling-block, and a rock which shall prove a hindrance.' They stumble because they do not accept the Message. This was the fate destined for them.