Charles Ellicott Commentary Luke 21:20

"But when ye see Jerusalem compassed with armies, then know that her desolation is at hand." — Luke 21:20 (ASV)

When you shall see Jerusalem compassed with armies.—See Notes on Matthew 23:15-21; Mark 13:14–19. This is St. Luke’s equivalent, possibly chosen as more intelligible for his Gentile readers, for “the abomination of desolation,” which we find in St. Matthew and St. Mark. As far as it goes, it favors the view that he and others saw the “abomination” in the presence of the invading armies.

On the other hand, it is possible, accepting, as we must accept, the thought of a substituted phrase, that we have one which, while it gives a partial explanation, fails to exhaust the meaning of the darker and more mysterious phrase. The occurrence of the word “desolation” in the latter clause of the verse, obviously favors the hypothesis now suggested.