John 6:60-65

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

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

62 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.

65 He said, "For this cause have I said to you that no one can come to me, unless it is given to him by my Father."