A.T. Robertson Commentary Luke 6:29

"To him that smiteth thee on the [one] cheek offer also the other; and from him that taketh away thy cloak withhold not thy coat also." — Luke 6:29 (ASV)

On the cheek (επ την σιαγονα). Matthew 5:39 has "right." Old word meaning jaw or jawbone, but in the N.T. only here and Mt 5:39, which see for discussion. It seems an act of violence rather than contempt. Sticklers for extreme literalism find trouble with the conduct of Jesus in Joh 18:22f. where Jesus, on receiving a slap in the face, protested against it.

Thy cloke (το ιματιον),

thy coat (τον χιτωνα). Here the upper and more valuable garment (ιματιον) is first taken, the under and less valuable χιτων last. In Mt 5:40 the process (apparently a legal one) is reversed.

Withhold not (μη κωλυσηις). Aorist subjunctive in prohibition against committing an act. Do not hinder him in his robbing. It is usually useless anyhow with modern armed bandits.