They answered him, Jesus of Nazareth. Jesus said unto them,
I am he.
And Judas also, who betrayed him, stood with them.
All Commentaries on John 18:5 Go To John 18
George Leo Haydock
Jesus here asks them, whom they were seeking, not as if He were ignorant of their errand, but to show them, that of their own power they could do nothing, because, though He, whom they sought, was present, and stood before them, yet, they did not know him. (Theophylactus)
The darkness of the night could not have been the reason why they did not see him, because, as the evangelist observes, they had lanterns and torches with them, and if they could not see him, at least they might have known him by his voice; for how could Judas, their leader, who was one of his own apostles, be unable to know him by his voice. (St. Chrysostom)