Recall that Jesus had been predicting for some time that He would be delivered up to suffer and die (Mat 16:21, 17:22-23, 20:18-19, 21:38, 26:2); what is different about His words now at His last Passover in regard to the same thing? I.e., what information did Jesus now announce about His approaching Passion that the twelve were now hearing for the first time? See Mat 26:21, and consider the difference between being delivered into the hands of men, and being betrayed by one of His closest disciples. Did the disciples doubt what Jesus said was true? What response did His words elicit from them? See Mat 26:22 and NAS note, Mar 14:18-20, Luk 22:23. Did they at that time have any idea that it was Judas about whom He was speaking? See Joh 13:21-30. Were they “deeply grieved” just because they now knew there was a traitor in their midst, or knowing their own human weaknesses and failures, as well as the righteous requirements of the Law and the holiness of their Master (cf. Luk 5:8), were they also grieved at the possibility that the one about whom He spoke could potentially be them? See again Mat 26:22 and Mar 14:19, and notice that while their individual question translated “Surely not I, Lord” in the NAS expects a negative answer, the sense isn’t necessarily so emphatic, as illustrated by the KJV “Lord, is it I?”, and could also be rendered, “It isn’t me, is it Lord?”.
Are we as deeply grieved by our own sinfulness to consider the possibility that we could deny or even betray our Lord by our words and deeds? What does this remind us about the importance of regularly approaching the throne of grace to receive mercy and find grace to help us in our time of need (Heb 4:16)? Knowing the weakness of our own flesh, do we pray regularly that we will not enter into such temptation, or do we pass it off and deceive ourselves that we could never fall away? Cf. Mat 26:31-35.
Was Peter as grieved about his own weakness and potential to deny the Lord as he perhaps ought to have been? In what way did that end up making his grief all the worse? See Mat 26:75, Joh 21:17. Who among the twelve responded in the same way as the others, but was certainly not as deeply grieved in his heart as he ought to have been? See Mat 26:25. In the end, did he escape the grief he ought to have had for his sins, or did his self-deception result in an even greater grief? See Mat 27:3-5. Does it ever pay to pretend that we are better than we actually are? Cf. Psa 32:3-5, Jam 4:6. What does this remind us about the importance of dealing honestly with our sins, however small we may suppose them to be, and confessing them to the Lord, and seeking His grace to overcome them, and not just justifying them as perhaps no worse than the sins of others? See Pro 28:13, Mat 7:13, Luk 13:24, 2Co 10:12, and consider that while God is patient with our weakness and merciful to forgive, and those who indulge their love for the world may appear to prosper for a time, it is the deceitful nature of sin that misleads us to suppose that our unrepentant pet sins will not condemn us to eternal grief as surely as those of others will also do to them; cf. Num 16:26.
Although the disciples didn’t necessarily doubt Jesus’ words that one of them would betray Him, what does their response indicate about their shock to hear such a thing? What does their astonishment indicate about how unthinkable it was that one of them would betray Jesus, and hence how heinous a crime it was even in the sight of man? Apart from Jesus being the righteous Son of God that makes it all the more unimaginable, what is it that makes such treachery so unthinkable even against much lesser men who are not nearly so perfect in advancing God’s goodness? Think: what does the closeness of the relationship indicate about the sincerity of the professed ideals and deeply held core beliefs that are then repudiated by such a betrayal? If one cannot be true to his own ideals, can he be true to anything? What does this again remind us about the sinfulness of sin that so corrupts a person as to no longer be true even to themselves? What does Jesus say in response to the disciples’ astonishment that one of them would betray Him? See Mat 26:23, and note that lacking the utensils we are accustomed to eating with today, the meal included dipping their individual pieces of bread into a community broth of nuts, raisins and figs (Robertson’s Word Pictures); cf. Joh 13:26. Again, what is the significance that it was one who had “dipped his hand” with Him in the bowl that would betray Him? Was the one who would betray Him only superficially associated with Him and His ministry, such as a spy who had infiltrated their ranks enough to overhear an ideal time to seize Him? Cf. Mat 10:1; contrast Mat 22:15-16. Again, how sinful must sin be to cause one to betray that in which he sincerely believes? How important then is it to be so deeply and sincerely grieved by our own sinfulness that we flee from all sin, and especially our love for worldly gain? Cf. Joh 12:5-6, 2Th 2:10, 1Ti 6:11, 1Jo 2:15-17.