John Gill Commentary Matthew 26:50

"And Jesus said unto him, Friend, [do] that for which thou art come. Then they came and laid hands on Jesus, and took him." — Matthew 26:50 (ASV)

And Jesus said to him, friend. Not in an ironical and sarcastic way, but because he pretended to be his friend, by saluting and kissing him, in the manner he had done; or rather, because Christ has always used him as his friend, his familiar friend, who had been of his councils, and had eaten at his table; and therefore this carried in it something very cutting, had Judas had any conscience, or sense of gratitude.

why have you come ? The Ethiopic version reads, "my friend, are you not come?" that is, are you come as my friend? Is your coming as a friend, or as an enemy? If as a friend, what means this company with swords and staves? If as an enemy, why this salutation and kiss? Or what is your end in coming at this time of night? What is your business here? You have left my company, and my disciples, what do you do here? The Syriac version reads it, "to that"; and the Arabic, "to this have you come?" to kiss me, and by a kiss to deliver me into the hands of my enemies? To which agrees what is said in Luke, "Judas, are you betraying the son of man with a kiss?" (Luke 22:48).

This he said, to let him know he knew him, and therefore he calls him by name; and that he knew his design in kissing him, and that what he was doing was against light and knowledge, knowing at the same time that he was the son of man, the true Messiah.

Then came they, and laid hands on Jesus, and took him ; that is, the multitude, the Roman band, the captains and officers of the Jews, when Judas had given the sign; though not till Christ had given them a specimen of his power, in striking them to the ground; to let them know, that Judas could never have put him into their hands, nor could they have laid hold on him, had he not thought fit to surrender himself to them. The seizing and apprehending him is related by Luke and John as after the following circumstance; though the Ethiopic version here reads, "they lift up their hands, and did not lay hold on the Lord Jesus".