John 8:27

But they did not understand that he spoke to them of the Father.

Isaiah 6:9

Then he said, Go and tell this people, Hear indeed, but do not understand; and see indeed, but do not perceive.

Isaiah 42:18-20

Hear, ye deaf; and look, ye blind, that ye may see.

Isaiah 59:10

We grope for the wall like the blind, and as if we had no eyes we walk by touch; we stumble at noonday as in the night; we are in graves as dead men.

John 8:43

Why do ye not understand my speech? even because ye cannot hear my word.

John 8:47

He that is of God hears God's words; ye therefore hear them not because ye are not of God.

Romans 11:7-10

What then? Israel has not obtained that which he seeks after; but the elect have obtained it, and the rest were blinded

2 Corinthians 4:3-4

But if our gospel is hid, it is hid to those that are lost,

Treasury of Scripture Knowledge

Summary

They understood not that he spake to them of the Father.

Bible References

General references

John 8:43
Why do ye not understand my speech? even because ye cannot hear my word.
Isaiah 6:9
Then he said, Go and tell this people, Hear indeed, but do not understand; and see indeed, but do not perceive.
Isaiah 42:18
Hear, ye deaf; and look, ye blind, that ye may see.
Isaiah 59:10
We grope for the wall like the blind, and as if we had no eyes we walk by touch; we stumble at noonday as in the night; we are in graves as dead men.
Romans 11:7
What then? Israel has not obtained that which he seeks after; but the elect have obtained it, and the rest were blinded
2 Corinthians 4:3
But if our gospel is hid, it is hid to those that are lost,