Hebrews 3:8
harden not your hearts as in the provocation, in the day of the trial in the wilderness,
Matthew 13:15
for the hearts of this people have become hard, and they hear imperfectly with their ears, and their eyes have they closed, lest they should see with their eyes, and hear with their ears, and understand with their hearts, and turn, and I should heal them.
Acts 19:9
But when some were hardened and believed not, speaking evil of the way before the multitude, he left them and separated the disciples from them, and reasoned day by day in the school of one Tyrannus.
Romans 2:5-6
But according to your hardness and unchanged heart you treasure up wrath for yourself in the day of wrath and of a revelation of the righteous judgment of God,
1 Corinthians 10:9
Neither let us try Christ, as some of them did and were destroyed by serpents.
Hebrews 3:12-13
See, brothers, that there be not at any time in any one of you an evil mind of unbelief in departing from the living God;