Hebrews 5:11
About him we have many words to say, and hard to interpret, seeing you have become dull of hearing.
2 Peter 3:16
as also in all of his letters, speaking in them of these things. In those, there are some things that are hard to understand, which the ignorant and unsettled twist, as they also do to the other Scriptures, to their own destruction.
Matthew 13:15
for this people's heart has grown callous, and their ears are dull of hearing, and they have closed their eyes; or else perhaps they might perceive with their eyes, hear with their ears, understand with their heart, and should turn again; and I would heal them.'
Isaiah 6:10
Make the heart of this people fat, and make their ears heavy, and shut their eyes; lest they see with their eyes, and hear with their ears, and understand with their heart, and turn again, and be healed."
Mark 8:17-18
He, perceiving it, said to them, "Why do you reason that it's because you have no bread? Do you not perceive yet, neither understand? Are your hearts hardened?
Mark 8:21
He asked them, "Do you not yet understand?"
Luke 24:25
Then he said to them, "O foolish ones, and slow of heart to believe in all that the prophets have spoken.
John 6:6
This he said to test him, for he himself knew what he would do.
John 16:12
"I have yet many things to tell you, but you cannot bear them now.
Acts 28:27
For this people's heart has grown callous. Their ears are dull of hearing. Their eyes they have closed. Lest they should see with their eyes, hear with their ears, understand with their heart, and would turn again, and I would heal them.'
1 Kings 10:1
When the queen of Sheba heard of the fame of Solomon concerning the name of the LORD, she came to prove him with hard questions.