'Hardened' in the Bible

for they understood not through the loaves: for their heart was hardened.

And Jesus knowing it, says to them, Why reason ye because ye have no bread? Do ye not yet perceive nor understand? Have ye your heart yet hardened?

He has blinded their eyes and hardened their heart, that they may not see with their eyes, and understand with their heart and be converted, and I should heal them.

But when some were hardened and disbelieved, speaking evil of the way before the multitude, he left them and separated the disciples, reasoning daily in the school of Tyrannus.

But encourage yourselves each day, as long as it is called To-day, that none of you be hardened by the deceitfulness of sin.