Jesus knew they were approaching in the darkness. The disciples did not know.
Judas is standing with the persecutors. We see that today. Sometimes, tragically, we see people who profess the Lord, and as the apostle Peter says in his second epistle, just as the dog returns to its vomit, and the sow returns to her wallowing in the mire, they go back to the world. They may insist they are still Christians, but you see them doing what the world does. You see they have gone back to all their rock music and their dances and their worldly ways. They are like Judas. It is a very solemn phrase, ‘And Judas also, which betrayed him, stood with them.’ You can tell a true Christian man or woman by who she or he stands with. What he associates with, what he does.