He, leaning back, as he was, on Jesus’ breast, asked him, “Lord, who is it?”
Verse 25. He then lying on Jesus' breast. This a different word from the one rendered leaning. It means falling back or laid his head back on the bosom of Jesus, so that he could speak to him privately without being heard by the others.
THE TRAITOR INDICATED--HE LEAVES THE SUPPER ROOM. (Joh 13:21-30) When Jesus had thus said, he was troubled in spirit, and testified, and said, Verily, verily, I say unto you, One of you shall betray me--The announcement of Joh 13:18 seems not to have been plain enough to be quite apprehended, save by the traitor himself. He will therefore speak it out in terms not to be misunderstood.
Commenting on John 13:21-30
He then lying--rather leaning over on Jesus' bosom. saith--in a whisper, "Lord, who is it?"