Mark 6:52
For they did not consider the matter of the loaves; but their heart was hardened.
Mark 3:5
And looking round on them with anger, being grieved for the hardness of their hearts, he saith to the man, Stretch forth thy hand. And he stretched it forth; and his hand was restored.
Mark 8:17-21
And knowing it, he saith to them, Why are ye reasoning, because ye have no bread? Do ye not yet perceive nor understand? Have ye your mind still blinded?
Matthew 16:9-11
Do ye not yet understand, nor remember the five loaves of the five thousand, and how many baskets ye took up?
Mark 7:18
And he saith to them, Are ye too so without discernment? Do ye not understand that whatever thing from without entereth into a man, cannot defile him?
Mark 16:14
Afterward he manifested himself to the eleven themselves, as they were reclining at table, and upbraided them with their unbelief and hardness of heart, because they did not believe those who had seen him after he had risen.
Luke 24:25
And he said to them, O dull of apprehension, and slow of heart to believe all that the Prophets have spoken!
Romans 11:7
What Israel seeketh after, that Israel did not obtain; but the elect obtained it, and the rest were hardened;