John 6:60
Many therefore of his disciples when they had heard this said, This is a hard word; who can hear it?
John 6:66
After this, many of his disciples went back and walked no more with him.
Matthew 11:6
And blessed is he who is not offended in me.
John 6:41-42
The Jews then murmured of him because he said, I AM the bread which descended from the heaven.
John 8:31
Then Jesus said to those Jews who had believed him, If ye abide in my word, ye shall be my disciples indeed;
John 8:43
Why do ye not understand my speech? even because ye cannot hear my word.
Hebrews 5:11
Of whom we have many things to say and difficult to declare, seeing ye are hard of hearing.
2 Peter 3:16
in almost all his epistles, speaking in them of these things, among which are some things that are hard to understand, which those that are ignorant and unstable twist, as they do also the other scriptures, unto their own destruction.