Charles Ellicott 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)

Friend, why have you come? The word for “friend” used here is the same as in Matthew 20:13 and Matthew 22:12. The terms “comrade” or the old English word “mate” come closer to its meaning. In classical Greek, it was used by fellow soldiers or sailors to address one another. Socrates also used it when conversing with his students (Plato, Republic i., p. 334).

It is likely that the short dialogue between our Lord and the officers, recorded in John 18:2-8, occurred immediately after this kiss was given.