Hebrews 5:11
Of whom great is the word to us, and difficult of interpretation to speak, since ye have been sluggish in the hearing.
2 Peter 3:16
As also in all the epistles, speaking in them of these things; in which are some things difficult to understand, which the unlearned and unstable pervert, as also the rest of the writings, to their own perdition.
Matthew 13:15
For the heart of this people has been thickened, and with their ears have they heard heavily, and their eyes have they closed; lest perhaps they should see with the eyes, and hear with the ears, and understand with the heart, and turn back, and I should heal them.
Isaiah 6:10
Make the heart of this people fat and their ears heavy, and blind their eyes, lest they shall see with their eyes and hear with their ears, and their heart shall understand and turn back and be healed to them.
Mark 8:17-18
And Jesus having known, says to them, Why reason ye with yourselves, because ye have no loaves? observe ye not yet, neither understand? have ye your heart yet hardened?
Mark 8:21
And he said to them, How do ye not understand
Luke 24:25
And he said to them, O ye unwise, and slow in heart to believe in all things which the prophets spake:
John 6:6
And this he said trying him: for himself knew what he was about to do.
John 16:12
I have yet many things to say to you, but ye cannot bear them now.
Acts 28:27
For the heart of this people was thickened, and with ears heard they heavily, and their eyes they closed; lest they should see with the eyes, and with ears should hear, and with the heart they should understand, and turn back, and I should heal them.
1 Kings 10:1
And queen Sheba heard the report of Solomon for the name of Jehovah, and she will come to try him in enigmas.