John 6:71

He spake of Judas Iscariot, [the son] of Simon
These are the words of the evangelist, pointing out the person Christ intended, lest any other should be suspected:

for he it was that should betray him:
as it was determined and foretold, and which Christ knew full well, and therefore said the above words:

being one of the twelve;
apostles, whom Christ had chosen, and which was an aggravation of his crime.