18 I speak not of you all: I know whom I have chosen: but that the scripture may be fulfilled, He that eateth bread with me hath lifted up his heel against me.

[I speak not of you all] This is a continuation of the discourse which was left off at the tenth verse, ..."And ye are clean, but not all.".

[I know whom I have chosen] I am not deceived in my choice; I perfectly foresaw everything that would happen. I have chosen Judas, not as a wicked man, nor with the intention that he should become such, but I plainly foresaw that he would give way to iniquity, deliver me into the hands of my enemies and bring ruin upon himself.

[That the Scripture may be fulfilled] Referring to Psalm 41:9.

19 Now I tell you before it come, that, when it is come to pass, ye may believe that I am he.

[That... ye may believe] The purpose of this prediction of his death was so that it would not be a surprise to them and, by the fact that his prediction was accurate, to reinforce their belief that he was Messiah.

20 Verily, verily, I say unto you, He that receiveth whomsoever I send receiveth me; and he that receiveth me receiveth him that sent me.

[He that receiveth whomsoever I send] Our Lord spoke this to comfort his disciples: he showed them that, although they would be rejected by many, they would be received by some. Receiving them as ambassadors of Christ was equal to receiving them as ambassadors of God. 2 Corinthians 5:20

21 When Jesus had thus said, he was troubled in spirit, and testified, and said, Verily, verily, I say unto you, that one of you shall betray me.

[shall betray me] Or a more literal translation of the Greek words, Will deliver me up. Judas had already made arrangement with the chief priests to betray Christ, and he was now about to carry out that betrayal by delivering him into their hands.

22 Then the disciples looked one on another, doubting of whom he spake.

[Looked one on another, doubting of whom he spake] Every one but Judas, confident of his own innocence, looked about upon all the rest, wondering who in that company could be such a traitor! Even Judas was not suspected by the others.

23 Now there was leaning on Jesus' bosom one of his disciples, whom Jesus loved.

[Now there was leaning on Jesus' bosom] The Jews, in those days, at their suppers, reclined, supported by their left arm, on couches placed round the table, as the Greeks and Romans did. On each couch there were two or three persons, and the head of one came near to the bosom of him who reclined above him on the same couch. The person here mentioned was John, the writer of this history, who, being more tenderly loved by Christ than the rest, had always this place at the table which was nearest to his Lord.

24 Simon Peter therefore beckoned to him, that he should ask who it should be of whom he spake.
25 He then lying on Jesus' breast saith unto him, Lord, who is it?
26 Jesus answered, He it is, to whom I shall give a sop, when I have dipped it. And when he had dipped the sop, he gave it to Judas Iscariot, the son of Simon.

[And when he had dipped the sop] While "Please pass the gravy" is a common request today, we also sometimes pass our empty plate to another to have a portion dipped out from a large serving bowl. It was not uncommon for the head of a table to break a piece of bread, dip it in the gravy or stew, and pass it to a tablemate. In this case Jesus used this action to identify who was about to betray him.

27 And after the sop Satan entered into him. Then said Jesus unto him, That thou doest, do quickly.

[Satan entered into him] He had entered into him before, and now he enters again, to strengthen him in his purpose of delivering up his master.

[That thou doest, do quickly.] What you plan to do is known to me. I permit it. Go quickly.

28 Now no man at the table knew for what intent he spake this unto him.
29 For some of them thought, because Judas had the bag, that Jesus had said unto him, Buy those things that we have need of against the feast; or, that he should give something to the poor.

Now no man at the table knew for what intent he spake this unto him. It is probable that the disciples did not hear the question John asked of Jesus nor Jesus' answer to John. It seems that even John did not connect the prediction of betrayal with Jesus' immediate instruction to Judas.

[Give something to the poor] While our Lord and his disciples lived on public charity; yet they gave alms out of what they had thus received. From this we learn that even those who live on charity themselves are expected to divide a little with those who are in deeper distress and want.

30 He then having received the sop went immediately out: and it was night.

[He...went immediately out] He set off to Jerusalem from Bethany, which was about two miles distant; and, under conduct of the prince of darkness, and in the time of darkness, did his work in darkness.

31 Therefore, when he was gone out, Jesus said, Now is the Son of man glorified, and God is glorified in him.

[Now is the Son of man glorified] I am the person appointed to redeem a lost world by my blood. I have already been glorified by this appointment, and am about to be further glorified by my death, resurrection and ascension.

32 If God be glorified in him, God shall also glorify him in himself, and shall straightway glorify him.

[And shall straightway glorify him] As he did, not only in the miracles wrought at this death, but also in that remarkable case mentioned in John 18:6, when the whole crowd that came to seize him were driven back with a word of his mouth, and fell to the ground.

33 Little children, yet a little while I am with you. Ye shall seek me: and as I said unto the Jews, Whither I go, ye cannot come; so now I say to you.

[Yet a litle while] The end of my life is at hand. Judas has gone to consummate his treason; I have but a few hours to be with you, and you shall be by and by scattered.

[Ye shall seek me] For a few days ye shall feel great distress because of my absence.

[Whither I go, ye cannot come] Your time is not up. You cannot come with me just now. You still have work to do in this world.

34 A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another.

A new commandment I give unto you] In what sense is this commandment new? "Thou shalt love thy neighbor as thyself" was a positive precept of the law, Leviticus 19:18. Our Lord answers this question, "Even as I have loved you." He not only loved his neighbor as himself, but more than himself, for he laid down his life for men.

35 By this shall all men know that ye are my disciples, if ye have love one to another.

[By this shall all men know] From this time forward this mutual love shall be the distinctive mark of all my disciples. When they love one another with pure hearts, fervently, even unto death, then shall it fully appear that they are disciples of that person who laid down his life for his sheep, and who became, by dying, a ransom for all.

36 Simon Peter said unto him, Lord, whither goest thou? Jesus answered him, Whither I go, thou canst not follow me now; but thou shalt follow me afterwards.

[Thou canst not follow me now] You have not faith strong enough to die for me, nor is your work yet done, but hereafter you shall suffer for my sake, and shall die in defence of my truth.

37 Peter said unto him, Lord, why cannot I follow thee now? I will lay down my life for thy sake.

[I will lay down my life for thy sake.] Peter was sincere, but did not know his own strength, or weakness. Christ must first die for Peter before Peter could die for him.

38 Jesus answered him, Wilt thou lay down thy life for my sake? Verily, verily, I say unto thee, The cock shall not crow, till thou hast denied me thrice.

[Till thou hast denied me thrice.] Let no man think he can do any thing good without the direct assistance of God. Peter's denial should be a warning to all self-confident persons; though there be sincerity and good will at the bottom, yet in trial these cannot perform that work which belongs to the power of God. We should determine what we wish to do, then look to God for power to execute.