John 8:27
"They understood not that he spake to them of the Father."
Cross References (ranked by relevance)
Isaiah 6:9
And he said, Go, and tell this people, Hear ye indeed, but understand not; and see ye indeed, but perceive not.
Isaiah 59:10
We grope for the wall like the blind, and we grope as if we had no eyes: we stumble at noon day as in the night; we are in desolate places as dead men.
John 8:47
He that is of God heareth God’s words: ye therefore hear them not, because ye are not of God.
John 8:43
Why do ye not understand my speech? even because ye cannot hear my word.