John 13:22

Then the disciples looked one to another
As persons surprised and astonished, and as scarce crediting what was said; not having had the least suspicion of anyone among them, that could be guilty of such an action; and expressing by their looks their detestation of, and indignation at so horrible an iniquity; or they looked one to another, to observe if they could, whether the countenance of anyone would discover who the person was:

doubting of whom he spake;
not being able to conceive and imagine, who the person was he had in view; from whence it appears, that Judas, to this time, had behaved outwardly as well as any of the other disciples; he had given no occasion, by his conduct, to suspect him more than any other: upon this broad intimation, or rather strong protestation which Christ made, that one of them should betray him, their eyes were not turned to him directly and particularly, but to one another.