John 12:4

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.