Hebrews 5:11
Concerning this {we have much to say and it is difficult to explain}, since you have become sluggish in hearing.
2 Peter 3:16
as [he does] also in all his letters, speaking in them about these [things], in which there are some [things] hard to understand, which the ignorant and unstable distort to their own destruction, as [they] also [do] the rest of the scriptures.
Matthew 13:15
For the heart of this people has become dull, and with their ears they hear with difficulty, and they have shut their eyes, so that they would not see with their eyes and hear with their ears and understand with their heart and turn, and I would heal them."
Isaiah 6:10
Make the heart of this people insensitive, and make its ears unresponsive, and shut its eyes so that it may not look with its eyes and listen with its ears and comprehend [with] its mind and turn back, and it may be healed [for] him."
Mark 8:17-18
And knowing [this], he said to them, "Why are you discussing that you have no bread? Do you not yet perceive or understand? Have your hearts been hardened?
Mark 8:21
And he said to them, "Do you not yet understand?"
Luke 24:25
And he said to them, "O foolish and slow in heart to believe in all that the prophets have spoken!
John 6:6
(Now he said this to test him, because he knew what he was going to do.)
John 16:12
I still have many [things] to say to you, but you are not able to bear [them] now.
Acts 28:27
For the heart of this people has become dull, and with [their] ears they hear with difficulty, and they have shut their eyes, lest they see with [their] eyes, and hear with [their] ears, and understand with [their] heart, and turn, and I would heal them." '
1 Kings 10:1
Now the queen of Sheba had heard of the fame of Solomon regarding the name of Yahweh, and she came to test him with hard questions.