Luke 24:25
And he said unto them, O ye void of understanding, and slow of heart to believe all that the prophets have spoken!
Mark 7:18
And he saith to them, Are ye also so defective of intelligence? Do you not consider, that every thing from without that entereth into a man, cannot make him unclean?
Mark 8:17-18
And Jesus knowing it said unto them, Why reason ye together, because ye have no loaves? Do ye not yet consider, nor understand? Have ye your heart yet hardened?
Mark 9:19
Then addressing him, he said, O faithless generation, how long shall I be with you? how long shall I bear with you? bring him to me.
Mark 16:14
Afterwards he shewed himself to the eleven, as they were sitting at table, and upbraided them for their infidelity and hardness of heart, because they did not believe those who had seen him after he was risen.
Hebrews 5:11-12
Concerning whom we have much to discourse, and of difficult interpretation to explain, seeing ye are dull of hearing.