John 6:60-65

60 Many therefore of his disciples, when they had heard [this], said, This is a hard saying; who can hear it?

61 When Jesus knew in himself that his disciples murmured at it, he said to them, Doth this offend you?

62 [What] if ye shall see the Son of man ascend up where he was before?

63 It is the spirit that reviveth; the flesh profiteth nothing: the words that I speak to you, [they] are spirit, and [they] are life.

64 But there are some of you that believe not. For Jesus knew from the beginning who they were that believed not, and who he was that would betray him.

65 And he said, Therefore I said to you, that no man can come to me, except it were given to him by my Father.