(Verse 14-15) - Ye also ought to wash - Some have understood this literally as instituting a religious rite which we ought to observe; but this was evidently not the design; because:

1. There is no evidence that Jesus intended it as a religious observance, like the Lord's Supper or the ordinance of baptism.

2. It was not observed by the apostles or the primitive Christians as a religious rite.

3. It was a rite of hospitality among the Jews, a common, well-known thing, and performed by servants.

4. It is the manifest design of Jesus here to inculcate a lesson of humility; to teach them by his example that they ought to condescend to the most humble offices for the benefit of others. They ought not to be proud, and vain, and unwilling to occupy a low place, but to regard themselves as the servants of each other, and as willing to befriend each other in every way. And especially as they were to be founders of the church, and to be greatly honored, he took this occasion of warning them against the dangers of ambition, and of teaching them, by an example that they could not forget, the duty of humility.

5. It is also a manifest design of the Lord here, possibly the main idea, to teach a lesson on the forgiveness of God as manifest in redemption.  We discussed this in the last devotional.

(Verse 18) - I speak not of you all - That is, in addressing you as clean, I do not mean to say that you all possess this character.

I know whom I have chosen - He here means evidently to say that he had not chosen them all, implying that Judas had not been chosen. As, however, this word is applied to Judas in one place John 6:70, “Have not I chosen you twelve, and one of you is a devil?” it must have a different meaning here from that which it has there. There it evidently refers to the apostleship. Jesus had chosen him to be an apostle, and had treated him as such. Here it refers to purity of heart, and Jesus implies that, though Judas had been chosen to the office of apostleship, yet he had not been chosen to purity of heart and life. The remaining eleven had been, and would be saved. It was not, however, the fault of Jesus that Judas was not saved, for he was admitted to the same teaching, the same familiarity, and the same office; but his execrable love of gold gained the ascendancy, and rendered vain all the means used for his conversion.

But that the scripture - These things have occurred in order that the prophecies may receive their completion. It does not mean that Judas was compelled to this course in order that the Scripture might be fulfilled, but that this was foretold, and that by this the prophecy did receive a completion. “The scripture.” This is written in Ps. 41:9. It is commonly understood of Ahithophel, and of the enemies of David who had been admitted to his friendship, and who had now proved ungrateful to him.

May be fulfilled - See the notes at Matt. 1:22. It is difficult to tell whether this prophecy had a primary reference to Judas, or whether it be meant that it received a more complete fulfillment in his case than in the time of David. The cases were similar; the same words would describe both events, for there was an exhibition of similar ingratitude and baseness in both cases, so that the same words would fitly describe both events.

He that eateth bread with me - To eat with one was a proof of friendship. See 2 Sam. 9:11; Matt. 9:11; Gen. 43:32. This means that Judas had been admitted to all the privileges of friendship, and had partaken of the usual evidences of affection. It was this which greatly aggravated his offence. It was base ingratitude as well as murder.

Hath lifted up his heel - Suidas says that this figure is taken from those who are running in a race, when one attempts to trip the other up and make him fall. It was a base and ungrateful return for kindness to which the Lord Jesus referred, and it means that he who had been admitted to the intimacies of friendship had ungratefully and maliciously injured him. Some suppose the expression means to lay snares for one others, to kick or injure a man after he is cast down (Calvin on Ps. 41:9). It is clear that it denotes great injury, and injury aggravated by the fact of professed friendship. It was not merely the common people, the open enemies, the Jewish nation that did it, but one who had received all the usual proofs of kindness. It was this which greatly aggravated our Savior's sufferings.

(Verse 20) - He that receiveth - This sentiment is found in the instructions which Jesus gave to his disciples in Matt. 10:40. Why he repeats it at this time cannot now be known. It is certain that it is not closely connected with the subject of his conversation. Perhaps, however, it was to show how intimately united he, his Father, his apostles, and all who received them were. They who received them received him, and they who received him received God. So he who betrayed him, betrayed, for the same reason, God. Hence Judas, who was about to betray him, was also about to betray the cause of religion in the world, and to betray God and his cause. Everything pertaining to religion is connected together. A man cannot do dishonor to one of the institutions of religion without injuring all; he cannot dishonor its ministers or the Savior without dishonoring God. And this shows that one prominent ground of the Savior's solicitude was that his Father might be honored, and one source of his deep grief at the treason of Judas was that it would bring injury upon the whole cause of religion in the world.

How do those facts apply to my life?:

 There is a great need for humility in the body of Christ today, particularly among its leaders.  We must be willing to humble ourselves and serve the real needs of others if we are to be of any great use to our Lord and King.