Mark 7:18
“Are you still so dull?” He asked. “Do you not understand? Nothing that enters a man from the outside can defile him,

Matthew 13:51
Have you understood all these things?” “Yes,” they answered.

Matthew 16:9-11
Do you still not understand? Do you not remember the five loaves for the five thousand, and how many basketfuls you gathered? / Or the seven loaves for the four thousand, and how many basketfuls you gathered? / How do you not understand that I was not telling you about bread? But beware of the leaven of the Pharisees and Sadducees.”

John 14:9
Jesus replied, “Philip, I have been with you all this time, and still you do not know Me? Anyone who has seen Me has seen the Father. How can you say, ‘Show us the Father’?

Luke 24:25
Then Jesus said to them, “O foolish ones, and slow of heart to believe all that the prophets have spoken!

Hebrews 5:11-12
We have much to say about this, but it is hard to explain, because you are dull of hearing. / Although by this time you ought to be teachers, you need someone to reteach you the basic principles of God’s word. You need milk, not solid food!

John 12:16
At first His disciples did not understand these things, but after Jesus was glorified they remembered what had been done to Him, and they realized that these very things had also been written about Him.

John 16:12
I still have much to tell you, but you cannot yet bear to hear it.

1 Corinthians 3:1-2
Brothers, I could not address you as spiritual, but as worldly—as infants in Christ. / I gave you milk, not solid food, for you were not yet ready for solid food. In fact, you are still not ready,

1 Corinthians 14:20
Brothers, stop thinking like children. In regard to evil be infants, but in your thinking be mature.

2 Peter 3:16
He writes this way in all his letters, speaking in them about such matters. Some parts of his letters are hard to understand, which ignorant and unstable people distort, as they do the rest of the Scriptures, to their own destruction.

Isaiah 6:9-10
And He replied: “Go and tell this people, ‘Be ever hearing, but never understanding; be ever seeing, but never perceiving.’ / Make the hearts of this people calloused; deafen their ears and close their eyes. Otherwise they might see with their eyes, hear with their ears, understand with their hearts, and turn and be healed.”

Jeremiah 5:21
“Hear this, O foolish and senseless people, who have eyes but do not see, who have ears but do not hear.

Ezekiel 12:2
“Son of man, you are living in a rebellious house. They have eyes to see but do not see, and ears to hear but do not hear, for they are a rebellious house.

Proverbs 28:5
Evil men do not understand justice, but those who seek the LORD comprehend fully.