Romans 9:18

Thus God has mercy on anyone just as he pleases, and he makes anyone stubborn just as he pleases.

John 12:40

He has blinded their eyes and made their hearts insensible, to prevent them seeing with their eyes and understanding with their hearts and turning for me to cure them.

Romans 1:28

Yes, as they disdained to acknowledge God any longer, God has given them up to a reprobate instinct, for the perpetration of what is improper,

2 Corinthians 2:16

to the one a deadly fragrance that makes for death, to the other a vital fragrance that makes for life. And who is qualified for this career?

2 Thessalonians 2:10-12

and with the full deceitfulness of evil for those who are doomed to perish, since they refuse to love the Truth that would save them.

1 Peter 2:8

a stone over which men stumble and a rock of offence; they stumble over it in their disobedience to God's word. Such is their appointed doom.

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 made their hearts insensible, to prevent them seeing with their eyes and understanding with their hearts and turning for me to cure them.
Romans 1:28
Yes, as they disdained to acknowledge God any longer, God has given them up to a reprobate instinct, for the perpetration of what is improper,
Romans 9:18
Thus God has mercy on anyone just as he pleases, and he makes anyone stubborn just as he pleases.
2 Corinthians 2:16
to the one a deadly fragrance that makes for death, to the other a vital fragrance that makes for life. And who is qualified for this career?
2 Thessalonians 2:10
and with the full deceitfulness of evil for those who are doomed to perish, since they refuse to love the Truth that would save them.
1 Peter 2:8
a stone over which men stumble and a rock of offence; they stumble over it in their disobedience to God's word. Such is their appointed doom.