John 12:39

Because of this they were not able to believe, that again Isaiah said,

John 5:44

how are ye able -- ye -- to believe, glory from one another receiving, and the glory that is from God alone ye seek not?

Isaiah 6:9-10

And He saith, 'Go, and thou hast said to this people, Hear ye -- to hear, and ye do not understand, And see ye -- to see, and ye do not know.

Isaiah 44:18-20

They have not known, nor do they understand, For He hath daubed their eyes from seeing, Their heart from acting wisely.

John 6:44

no one is able to come unto me, if the Father who sent me may not draw him, and I will raise him up in the last day;

John 10:38

and if I do, even if me ye may not believe, the works believe, that ye may know and may believe that in me is the Father, and I in Him.'

2 Peter 2:14

having eyes full of adultery, and unable to cease from sin, enticing unstable souls, having an heart exercised in covetousnesses, children of a curse,

Treasury of Scripture Knowledge

Summary

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

Bible References

They

John 5:44
how are ye able -- ye -- to believe, glory from one another receiving, and the glory that is from God alone ye seek not?
John 6:44
no one is able to come unto me, if the Father who sent me may not draw him, and I will raise him up in the last day;
John 10:38
and if I do, even if me ye may not believe, the works believe, that ye may know and may believe that in me is the Father, and I in Him.'
Isaiah 44:18
They have not known, nor do they understand, For He hath daubed their eyes from seeing, Their heart from acting wisely.
2 Peter 2:14
having eyes full of adultery, and unable to cease from sin, enticing unstable souls, having an heart exercised in covetousnesses, children of a curse,

General references

Exodus 10:20
and Jehovah strengtheneth the heart of Pharaoh, and he hath not sent the sons of Israel away.
Deuteronomy 29:4
and Jehovah hath not given to you a heart to know, and eyes to see, and ears to hear, till this day,
John 1:5
and the light in the darkness did shine, and the darkness did not perceive it.
John 9:18
and he said -- 'He is a prophet.' The Jews, therefore, did not believe concerning him that he was blind and did receive sight, till that they called the parents of him who received sight,
John 10:37
if I do not the works of my Father, do not believe me;