John 12:39

Therefore they could not believe, because Isaiah said again,

John 5:44

How can you believe, you who receive honor from one another and do not seek the honor that comes from God only?

Isaiah 6:9-10

And He said, Go, and tell this people, You hear indeed, but do not understand; and seeing you see, but do not know.

Isaiah 44:18-20

They have not known nor understood; for He has shut their eyes so that they cannot see; and their hearts so that they cannot understand.

John 6:44

No one can come to Me unless the Father who has sent Me draw him, and I will raise him up at the last day.

John 10:38

But if I do, though you do not believe Me, believe the works so that you may know and believe that the Father is in Me, and I in Him.

2 Peter 2:14

having eyes full of adultery and never ceasing from sin, alluring unstable souls, having a heart exercised with covetousness. They are cursed children

Treasury of Scripture Knowledge

Summary

Therefore they could not believe, because that Esaias said again,

Bible References

They

John 5:44
How can you believe, you who receive honor from one another and do not seek the honor that comes from God only?
John 6:44
No one can come to Me unless the Father who has sent Me draw him, and I will raise him up at the last day.
John 10:38
But if I do, though you do not believe Me, believe the works so that you may know and believe that the Father is in Me, and I in Him.
Isaiah 44:18
They have not known nor understood; for He has shut their eyes so that they cannot see; and their hearts so that they cannot understand.
2 Peter 2:14
having eyes full of adultery and never ceasing from sin, alluring unstable souls, having a heart exercised with covetousness. They are cursed children

General references

Exodus 10:20
But Jehovah hardened Pharaoh's heart, and he did not let the sons of Israel go.
Deuteronomy 29:4
Yet Jehovah has not given you a heart to perceive, and eyes to see, and ears to hear, until today.
John 1:5
And the light shines in the darkness, and the darkness did not overtake it.
John 9:18
But the Jews did not believe concerning him, that he had been blind and had received his sight, until they called the parents of him having received sight.
John 10:37
If I do not do the works of My Father, do not believe Me.