One of you will betray me. To render the treachery of Judas more detestable, he points out the aggravated baseness of it by this circumstance, that he was meditating the act of betraying him while he sat with him at the holy table. For if a stranger had done this, it would have been more easily endured; but that one of his intimate friends should form such a design, and -- what is more -- that, after having entered into an infamous bargain, he should be present at the sacred banquet, was incredibly monstrous. And therefore Luke employs a connecting particle which marks a contrast: but yet, (plen) lo, the hand of him that betrayeth me. And though Luke adds this saying of Christ after the supper was finished, we cannot obtain from it any certainty as to the order of time, which, we know, was often disregarded by the Evangelists. Yet I do not deny that it is probable that Judas was present, when Christ distributed to his disciples the symbols of his flesh and blood.

As they did eat - The account contained in these verses is also recorded in Mark 14:18-21; Luke 22:21-23; John 13:21-22. John says that before Jesus declared that one of them should betray him, "he was troubled in spirit, and testified;" that is, he "felt deeply" in view of the greatness of the crime that Judas was about to commit, and the sufferings that he was to endure, and "testified," or gave utterance to his inward feelings of sorrow.

One of you shall betray me - Or, will deliver me up. Judas had already betrayed him, Matthew 26:15, and he was now about to deliver him into the hands of the chief priests, according to the agreement he had made with them.

And as they did eat,.... The passover lamb, the unleavened bread, and bitter herbs: he said it was usual, whilst they were thus engaged, to discourse much about the reason and design of this institution. What they talked of may be learnt from what follows (y):
"it is an affirmative precept of the law, to declare the signs and wonders which were done to our fathers in Egypt, on the night of the fifteenth of Nisan, according to Exodus 13:3, "remember this day", &c. and from whence on the night of the fifteenth? from Exodus 13:8, "and thou shalt show thy son", &c. at the time that the unleavened bread, and bitter herbs lie before thee. And though he has no son, or though they are wise, and grown up, they are bound to declare the going out of Egypt; and everyone that enlarges, or dwells long on the things that happened and came to pass, lo! he is praiseworthy. It is a command to make known to children, even though they do not ask; as it is said, "and thou shalt show thy son": according to the son's knowledge, his father teaches him; how if he is a little one, or foolish? he says to him, my son, all of us were servants, as this handmaid, or this servant, in Egypt; and on this night the holy, blessed God redeemed us, and brought us into liberty: and if the son is grown up and a wise man, he makes known to him what happened to us in Egypt, and the wonders which were done for us by the hands of Moses, our master; all according to the capacity of the son. And it is necessary to make a repetition on this night, that the children may see, and ask, and say, how different is this night from all other nights? until he replies to them, and says to them, so and so it happened, and thus and thus it was.--If he has no son, his wife asks him; and if he has no wife, they ask one another, how different is this night? and though they are all wise men, everyone asks himself alone, how different is this night? and it is necessary to begin with reproaches, and end with praise, how? he begins and declares, how at first our fathers were in the days of Terah, and before him, deniers (of the divine being), and wandering after vanity, and following idolatrous worship; and he ends with the law of truth, how that God brought us near to himself, and separated us from the nations, and caused us to draw nigh to his unity; and so begins and makes known, that we were servants to Pharaoh in Egypt, and all the evils he recompensed us with; and ends with the signs and wonders which were wrought for us, and with our liberties: and he that expounds from--"a Syrian was my father, ready to perish": till he has finished the whole section: and every one that adds and enlarges in expounding this section, lo! he is praiseworthy. And everyone that does not say these three words on the night of the fifteenth, cannot be excused from blame; and they are these, the passover, the unleavened bread, and the bitter herbs: "the passover", because God passed over the houses of our fathers in Egypt, as it is said, Exodus 12:27, "the bitter herbs", because the Egyptians made bitter the lives of our fathers in Egypt: "the unleavened bread", because they were redeemed: and these things all of them are called the declaration, or showing forth.''
Christ now took up some part of the time, at least, whilst they were eating, in discoursing with his disciples about the traitor:
he said, verily I say unto you, that one of you shall betray me; meaning to the chief priests and Scribes, who should condemn him to death, and deliver him to the Gentiles, to be mocked, scourged, and crucified, as he had told them some time before, Matthew 20:18, though he did not tell them as now, that it should be done by one of them; he had indeed signified as much as this two days before, at the supper in Bethany, but none seemed to understand whom he meant, but Peter and John, and the thing wore off their minds; and therefore he mentions it again to them, with great seriousness, and in the most solemn manner, declaring it as a certain and undoubted truth.
(y) Maimon. ib. c. 7. sect. 1, 2, 3, 4, 5. Vid. c. 8. 2, 3, 4, 5. & Haggadah Shel. Pesach. p. 5, 6, 7, 8.

One of you shall betray me. The meal, opened with "blessing," seems to have proceeded with solemn silence after it began, until the silence was broken by these startling words.