Matthew 17:17
Jesus answered and said: faithless and perverse generation, how long shall I be with you? How long shall I bear with you? Bring him hither to me.
Matthew 17:20
And Jesus said to them: Because of your unbelief. For verily I say to you, If you have faith like a grain of mustard-seed, you shall say to this mountain, Be removed from this place to that, and it shall be removed: and nothing shall be impossible for you.
Mark 8:17-18
And Jesus perceived it, and said to them: Why do you reason, because you have no bread? Do you not yet perceive, nor understand? Is your heart still hardened?
Hebrews 12:5
and you have forgotten the exhortation which is addressed to you as to sons: My son, despise not the chastening of the Lord, nor faint when you are reproved by him.