‘Simon Peter therefore gestured to him, and said to him, “Tell who it is he is speaking about”. He, leaning back as he was on Jesus' breast, says to him, “Lord, who is it?” Jesus therefore answers, “He it is for whom I will dip the sop and give it to him.” So when he had dipped the sop he takes and gives it to Judas, the son of Simon Iscariot.'
At Jesus' words it was typical of Peter that he rushed in when all others were silent. All were aware that something solemn was in the air, and they were dumbstruck. But not Peter. Yet even he kept it to a question put in privacy. He hinted to John by a signal that he should question further. It would seem that this episode was private between the three of them.
So John, leaning back as he was, close to Jesus (literally ‘on Jesus' breast'), says to him, “Lord, who is it?” Then Jesus answers, “It is the one for whom I will dip the sop (broken bread with bitter herbs dipped in a sauce) and give it to him”. It is possible, in fact, that Peter assumed that Jesus had already told John who it was. But He had clearly not done so. Alternately his question may have been deliberately indirect because he did not want Jesus to think that he was asking Him or anyone else a direct question. It was an indirect suggestion that John ask Jesus evidenced by his hand signal. (This is a clear sign of an eyewitness account). Either way John gets the point and asks, ‘Lord, who is it?'
It is not accidental that all were now described as calling Jesus ‘Lord'. By it the writer wishes us to recognise that it was the Lord of glory with Whom the disciples were fellowshipping. While they may have been using a courtesy title which could be translated ‘lord', it must have had a deeper meaning even then. Thus it bears a double meaning.
Jesus did not denounce the traitor openly. Now that Judas has delivered himself into Satan's hands He wished him to carry out his evil deed. Thus while Jesus made known to John who it was, He did not bring home to him the importance of the betrayal in mind, and also kept the fact from the other disciples. (This must be so due to what immediately follows). John may well have been thinking that Jesus was referring to Judas' misuse of the funds, especially when He immediately appeared to send Judas off to buy provisions. He may have thought that Jesus was ‘on to him'. So when Jesus quietly told him that it was the one to whom He would give a piece of dipped bread, John would have no cause to react and prevent Judas from going. He might well have thought that if he did so he would spoil Jesus' plan.
Then Jesus dipped the bread into the mixture of bitter herbs, vinegar and salt (or alternately one of mashed fruit, water and vinegar), and gave it to Judas. Outwardly, as far as the rest were concerned, this was the final titbit at the end of the meal given to a favoured friend. John, aware that Jesus did not wish the matter known, and not realising how important it was, remained silent (he would not realise that the betrayal was to be fatal, nor that it would happen immediately. Indeed he would see Jesus' calmness as indicating the opposite). But there was one other who knew, apart from Jesus, how deep was the betrayal, and that was Judas. This final offering of the titbit to Judas was a final chance for him to recognise Jesus' goodwill towards him. It indicated that Jesus had not given up until there was no hope at all.