This was John. He tells us later. John 21:20, 23-24:
(20) Peter, turning around, saw the disciple whom Jesus loved following [them;] the one who also had leaned back on His bosom at the supper and said, "Lord, who is the one who betrays You?" . . . Therefore this saying went out among the brethren that that disciple [the disciple Jesus loved] would not die; yet Jesus did not say to him that he would not die, but [only,] "If I want him to remain until I come, what [is that] to you?" (24) This is the disciple who is testifying to these things and wrote these things, and we know that his testimony is true.
Where each disciple sat may have been based upon some type of ranking system, similar to the custom of the Pharisees. Earlier in Jesus' ministry, James and John asked to sit on Jesus' right and left hand in His kingdom. (Mark 10:35-45 and Matthew 20:20-22). They were asking to be honored. They had no idea what they were asking for.
<,p>This may have been a common problem among the disciples. They expected Jesus to raise up an army and set up an earthly kingdom. This is what most of the people in Israel envisioned. As a result, they were vying for the best positions. of power or prestige in this kingdomLuke tells us that on the night of the Last Supper, a dispute broke out among the disciples about who among them was the greatest. How sad. Jesus was already stressed as he faced the ordeal ahead of him, and the disciples were concerned about who was ranked higher than the others. If you were there, you might wonder whether the disciples had learned anything.
Luke: 22: 24-27A dispute also arose among them as to which of them was considered to be greatest. 25 Jesus said to them, “The kings of the Gentiles lord it over them; and those who exercise authority over them call themselves Benefactors. 26 But you are not to be like that. Instead, the greatest among you should be like the youngest, and the one who rules like the one who serves. 27 For who is greater, the one who is at the table or the one who serves? Is it not the one who is at the table? But I am among you as one who serves.
How did this silly dispute start? It is possible that the problem arose as they were trying to decide where each of them was going to sit.
Apparently, Judas won the dispute. Based on the text, Judas was sitting next to Jesus on His left, in the position of honor. Jesus shared food with him and spoke privately with him. John was on His right. It says that John leaned upon Jesus' breast. Peter may have been at the lowest place, across from John. When Jesus told them that one of them would betray Him, Peter gestured to John to see if he knew who would betray Jesus.