Mark 4:12

Deuteronomy 29:4 NIV
But to this day the Lord has not given you a mind that understands or eyes that see or ears that hear.

Isaiah 44:18 NIV
They know nothing, they understand nothing; their eyes are plastered over so they cannot see, and their minds closed so they cannot understand.

Isaiah 6:9-10 NIV
He said, “Go and tell this people: “‘Be ever hearing, but never understanding; be ever seeing, but never perceiving.’ Make the heart of this people calloused; make their ears dull 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 NIV
Hear this, you foolish and senseless people, who have eyes but do not see, who have ears but do not hear:

John 12:37-41 NIV
Even after Jesus had performed so many signs in their presence, they still would not believe in him. This was to fulfill the word of Isaiah the prophet: “Lord, who has believed our message and to whom has the arm of the Lord been revealed?” For this reason they could not believe, because, as Isaiah says elsewhere: “He has blinded their eyes and hardened their hearts, so they can neither see with their eyes, nor understand with their hearts, nor turn—and I would heal them.” Isaiah said this because he saw Jesus’ glory and spoke about him.

Matthew 13:14-15 NIV
In them is fulfilled the prophecy of Isaiah: “‘You will be ever hearing but never understanding; you will be ever seeing but never perceiving. For this people’s heart has become calloused; they hardly hear with their ears, and they have closed their eyes. Otherwise they might see with their eyes, hear with their ears, understand with their hearts and turn, and I would heal them.’