John 6:62 WEB

⁶⁰  Therefore many of his disciples, when they heard this, said, 'This is a hard saying! Who can listen to it?'

⁶¹  But Jesus knowing in himself that his disciples murmured at this, said to them, 'Does this cause you to stumble?

⁶²  Then what if you would see the Son of Man ascending to where he was before?

⁶³  It is the spirit who gives life. The flesh profits nothing. The words that I speak to you are spirit, and are life.

⁶⁴  But there are some of you who don't believe.' For Jesus knew from the beginning who they were who didn't believe, and who it was who would betray him.