A.T. Robertson Commentary Matthew 26:47

"And while he yet spake, lo, Judas, one of the twelve, came, and with him a great multitude with swords and staves, from the chief priest and elders of the people." — Matthew 26:47 (ASV)

While he yet spake (ετ αυτου λαλουντος). It was an electric moment as Jesus faced Judas with his horde of helpers as if he turned to meet an army.

Let us go (αγωμεν), Jesus had said. And here he is. The eight at the gate seemed to have given no notice. Judas is described here as "one of the twelve" (εις των δωδεκα) in all three Synoptic Gospels (Matthew 26:47; Luke 22:47). The very horror of the thing is thus emphasized, that one of the chosen twelve apostles should do this dastardly deed.

A great multitude (οχλος πολυς). The chief priests and Pharisees had furnished Judas a band of soldiers from the garrison in Antonia (John 18:3) and the temple police (Luke 22:52) with swords (knives) and staves (clubs) with a hired rabble who had lanterns also (John 18:3) in spite of the full moon. Judas was taking no chances of failure for he well knew the strange power of Jesus.