John 6:59-71

These things said he in the synagogue, as he taught in Capernaum. Many therefore of his disciples, when they heard this, said, This is a hard saying; who can hear it? But Jesus knowing in himself that his disciples murmured at this, said unto them, Doth this cause you to stumble? What then if ye should behold the Son of man ascending where he was before? It is the spirit that giveth life; the flesh profiteth nothing: the words that I have spoken unto you are spirit, and are life. But there are some of you that believe not. For Jesus knew from the beginning who they were that believed not, and who it was that should betray him. And he said, For this cause have I said unto you, that no man can come unto me, except it be given unto him of the Father. Upon this many of his disciples went back, and walked no more with him. Jesus said therefore unto the twelve, Would ye also go away? Simon Peter answered him, Lord, to whom shall we go? thou hast the words of eternal life. And we have believed and know that thou art the Holy One of God. Jesus answered them, Did not I choose you the twelve, and one of you is a devil? Now he spake of Judas the son of Simon Iscariot, for he it was that should betray him, being one of the twelve.