John 14:5
Thomas said to him: Lord, we do not know where you go. How do we know the way?
John 11:16
Thomas, who is called Didymus, said to his fellow disciples: Let us also go that we may die with him.
Mark 8:17-18
Hearing this Jesus said: Why do you reason about having no bread? Do you not understand? Are your hearts dull of understanding?
Mark 9:19
Jesus then said: O faithless generation. How long will I be with you? How long must I put up with you? Bring him to me.
Luke 24:25
He said to them: You are foolish men. You are slow of heart to believe in all that the prophets have spoken!
John 15:12
This is my commandment, that you love one another, even as I have loved you.
John 20:25-28
The other disciples therefore said to him: We have seen the Lord. He said: Unless I feel the print of the nails in his hands and put my hand into his side, I will not believe.
Hebrews 5:11-12
We have many things to say about him and it is hard to explain it to you, for you are dull of hearing (slow to learn).