John the Apostle
John 13:24ESV·traditional attribution

so Simon Peter motioned to him to ask Jesus of whom he was speaking.

Matthew Henry Presbyterian @wholebiblehenry

We have here the discovery of Judas's plot to betray his Master. Christ knew it from the beginning; but now first he discovered it to his disciples, who did not expect Christ should be betrayed, though he had often told them so, much less did they suspect that one of them should do it. Now here, I.

Commenting on John 13:18-30

John Gill Reformed Baptist @doctorgill

Simon Peter therefore beckoned to him,.... Peter perhaps lay at a distance from Christ, or in some such position, that he could not whisper to him himself; and besides, knew that John might use more freedom, as he was admitted to more familiarity with him; and being at some distance also from him, he beckoned to him; which was usually done at meals, when they...

Jamieson-Fausset-Brown Reformed @jfbcommentary

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