John 6:71
He was speaking about Judas, the son of Simon Iscariot. For although Judas was one of the Twelve, he was later to betray Jesus.
What it says
John identifies Judas, son of Simon Iscariot, as the one who would later betray Jesus.
What it is doing
The verse names Judas and states the betrayal in advance.
In context
67So Jesus asked the Twelve, “Do you want to leave too?” 68Simon Peter replied, “Lord, to whom would we go? You have the words of eternal life. 69We believe and know that You are the Holy One of God. ” 70Jesus answered them, “Have I not chosen you, the Twelve? Yet one of you is a devil!” 71He was speaking about Judas, the son of Simon Iscariot. For although Judas was one of the Twelve, he was later to betray Jesus.