John 6: 60-71
Many of his disciples, when they heard it, said, "This is a hard saying; who can listen to it?" But Jesus, knowing in himself that his disciples murmured at it, said to them, "Do you take offense at this? Then what if you were to see the Son of man ascending where he was before? It is the spirit that gives life, the flesh is of no avail; the words that I have spoken to you are spirit and life. But there are some of you that do not believe."
For Jesus knew from the first who those were that did not believe, and who it was that would betray him. And he said, "This is why I told you that no one can come to me unless it is granted him by the Father." After this many of his disciples drew back and no longer went about with him. Jesus said to the twelve, "Do you also wish to go away?" Simon Peter answered him, "Lord, to whom shall we go? You have the words of eternal life; and we have believed, and have come to know, that you are the Holy One of God."
Jesus answered them, "Did I not choose you, the twelve, and one of you is a devil?" He spoke of Judas the son of Simon Iscariot, for he, one of the twelve, was to betray him.