The Great Commentary of Cornelius à Lapide
John 13:21
When He had said these things, Jesus was troubled in spirit, and testified (openly and plainly), saying, Verily, I say unto you, that one of you will betray Me. In the Syriac, "These things said Jeschua, and groaned in spirit, and testified and said, Amin, amin, I say to you," κ.τ.λ. In the Arabic Version "was moved in spirit." This emotion, then, was an immense grief and indignation at the crime of Judas. Christ was pained in the innermost feelings of His soul, and groaned in spirit for the enormity of this crime as well as for the perdition of Judas. And this sorrow he did not suffer involuntarily, but admitted it of His free will, and took it upon Him at this point of His own accord, as He did at the death of Lazarus. See commentary on John 11:33.
The question arises here, Did this prediction of Christ take place before or after the institution of the Eucharist? John omits all mention of that event, it having been narrated fully by the other Evangelists. Matthew and Mark put the prediction before the institution of the Eucharist in order of time, but Luke puts it after.
There are three probable opinions on this point. The first is that of Jansenius and Francis Lucas, who think that Christ predicted the treason of Judas after the Eucharist, as Luke has it, and that Matthew and Mark, in making it come before, anticipate intentionally. The reason for this view is that if Christ had predicted the treason of Judas before the institution of the Eucharist, He would have disturbed the minds of the apostles, moved them to anger, and rendered their dispositions for its reception less collected than would have been fitting. But this is not conclusive. For Christ before the Eucharist foretold His passion and death, and this disturbed the apostles far more: and soon after the Eucharist as these interpreters themselves admit He foretold the treason of Judas, and this disturbed them then, so that they did not duly dispose themselves for that recollection which is proper after Communion. Then again this prediction would, before the Eucharist, have had the force of deterring Judas from his crime, as well as producing compunction in the hearts of the apostles and making them all careful to examine each one his own conscience, lest Christ should there find anything to bring to light and complain of, as He did the crime of Judas.
The second opinion is that of Baronius (Anno Dni. 34, ch. 58). He thinks that Christ made this prediction before the institution of the Eucharist, as Matthew and Mark have it. Baronius, then, is of opinion that the events took place in the order given by John, namely, that after the washing of the feet, Jesus spoke of His betrayal, that it was then that He gave John the sign of the morsel dipped in the dish, but that, as for Judas having gone out immediately after he had taken the morsel, we are not to take the phrase as meaning without any delay in point of time, but that, driven on by a kind of madness, he did not wait for the lengthy discourse which our Lord made after the Supper. For S. Luke clearly bears witness that Judas stayed with the others until the end of the Communion; and after this, according to the Jewish ceremonial, it would seem that nothing was left on the table in which the morsel of bread could have been dipped, so, too, it seems impossible to say that this morsel of bread was the Eucharist. But then Judas, after taking the morsel, did go out immediately, nay, that very moment according to the Syriac. He did not, then, wait for the lengthy Communion of the apostles, if that took place after the incident of the morsel. Hence it is with greater likelihood that other upholders of this view maintain that the morsel given to Judas by Christ was itself the Eucharist; and he, driven, as it were, to madness by the devil when he had received it, unworthily, straightway went forth to carry out the crime he was meditating. Moreover, during and after the institution of the Eucharist Christ reclined at the table, and there, as Luke has it, foretold the treason of Judas. It is, therefore, altogether probable that the table had not yet been removed, but that on it there remained bread and fragments of food out of which Christ could take the bread which He dipped and gave to Judas.
The third opinion, therefore, holding a middle place between the two former, seems to be the more correct namely, that Christ both foretold His betrayal by Judas before the Eucharist, and repeated the prediction after it; and this both because He felt the atrocity of the crime, and was, as John here says, disturbed in spirit by it, again, that He might place his own wickedness before Judas, show him that He knew of it, and deter him from carrying it out, and also to prepare and fortify the minds of the Apostles, that when they should soon after see the actual betrayal and the capture of Jesus they might not be shocked, but might persevere with constancy in His faith. In this way we best reconcile Matthew and Mark with Luke. This is the expressed view of S. Augustine (De Consensu Evang., bk. iii. ch. 1), of Euthymius, and of Toletus, who say that the order of events was as follows. The Supper of the Paschal Lamb having been finished, and the ordinary Supper begun, Christ, while they were supping, arose and washed the feet of His disciples; then, reclining once more, He said all these things which John narrates; being troubled in spirit He speaks of His betrayer, and they all ask, one by one, "Is it I?" Judas receiving the answer, "Thou hast said."
Next He institutes the Eucharist, and this being done, and the Mystery having been celebrated, He again speaks of His betrayer, as Luke relates, ch. xxii. "Nevertheless," He says, "behold, the hand of him that betrayeth Me is with Me at table," &c. Then Peter asks John, "Who is it of whom He speaks?" and John asking Jesus, receives the answer, "He to whom I shall offer the bread when I have dipped it." And after this morsel Satan entered into Judas, and he went away; and when he went away, and the Supper was quite finished, Christ made to His disciples the wonderful discourse shortly after recorded by John.