Hebrews 5:11
Concerning him I have much to say, and much that is hard to make clear to you, because you have grown dull of hearing.
2 Peter 3:16
It is the same in all his letters when he speaks of these things. There are indeed some things in his letters hard to understand, which the ignorant and the shifty wrest, as also they do the other Scriptures, to their own destruction.
Matthew 13:15
For the heart of his people is made fat, Their ears are dull of hearing; Their eyes, too, have they closed, Lest some day their eyes should perceive, And their ears should hear, And their heart should understand and turn, And I should heal them.
Mark 8:17-18
"Why are you arguing together because you have no bread? Do you not yet perceive and understand?
Mark 8:21
"Do you not yet understand?" he said.
Luke 24:25
"O foolish men," said Jesus, "slow of heart to believe all that the prophets have spoken!
John 6:6
He said this to test him, for he himself knew what he intended to do.
John 16:12
"I have yet many things to say to you, but you cannot bear them just now.
Acts 28:27
For this people's heart is grown obtuse, Their ears are heavy of hearing, Their eyes have they closed, Lest they should see with their eyes And hear with their ears, Lest they understand with their heart, And turn again, and heal them.