Albert Barnes 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. It seems strange to us that Jesus should give the endeared name friend to a man whom he knew was his enemy and who was about to betray him.

It should be remarked, however, that this is a fault of our language, not of the original. In Greek, there are two words that our translators have rendered as friend: one implying affection and regard, the other not. One is properly translated as friend; the other more closely expresses what we mean by companion.

It is this latter word that is used for the disaffected laborer in the vineyard: Friend, I do thee no wrong (Matthew 20:13); for the guest who was not wearing a wedding garment in the parable of the marriage feast (Matthew 22:12); and for Judas in this instance.

Why have you come? This was said, not because he was ignorant of why he had come, but probably to fill the mind of Judas with the consciousness of his crime and, by a striking question, to compel him to think of what he was doing.