One of his disciples, therefore, saith. Next follows the murmuring of Judas, which Matthew (Matthew 16:8) attributes to the disciples indiscriminately, and Mark (Mark 14:4) to some of them; but it is customary in Scripture to apply to many, by way of synecdoche, what belongs to one or to a few. Yet I think it is probable, that the murmuring proceeded from Judas alone, and that the rest were induced to give him their assent, as murmurings, by fanning a flame, easily kindle in us a variety of dispositions; and more especially, as we are too prone to form unfavorable judgments, slanders are readily embraced by us. But the credulity which the Spirit of God reproves in the Apostles is a warning to us not to be too easy and credulous in listening to calumnious statements.

Which should betray him - Greek, "who was to betray him" - that is, who would do it.

Then saith one of his disciples,.... Who had no true love for his master, was an hypocrite, and a covetous person:
Judas Iscariot; so called, to distinguish him from another Judas, an apostle; See Gill on Matthew 10:4.
Simon's son; this is omitted in the Vulgate Latin, Syriac, Persic, and Ethiopic versions; See Gill on John 13:2;
which should betray him; and so he did; this was pre-determined by God, foretold in prophecy, and foreknown by Christ; and is observed here, to show the temper and character of the man.

Judas . . . who should betray him--For the reason why this is here mentioned, see on Mark 14:11.