They. — Quite vague and general, like the French on. The plural is so used frequently in St. Luke (Luke 12:11; Luke 12:20, margin; Luke 16:9, probably; Luke 23:29-31). Of course, however, no Christian could say so, for they are ever on the watch, so that “they” will mean “the world.” The word “for” at the beginning of the verse should (according to the best MSS.) be struck out — the abruptness helps to enforce the lesson.
Peace and safety. — Carrying on the thought suggested by the word “night; they are taking their repose in security, without dreaming of any interruption to their slumbers. Is it possible that there may here be a faint recollection of the parable related in Matthew 25:1-13?
Destruction cometh upon them. — Literally, stands over them; or takes its stand over them; presents itself. The present tense is used for the sake of a more vivid effect. The extreme similarity of this passage to Luke 21:34 (with other indications) inclines Bishop Wordsworth to think that the Thessalonians had the Gospel of St. Luke to refer to.
As travail. — A common Oriental simile to express not only suddenness, but horror also. Theodoret fairly says, “The woman with child knows that she has the child to bear, but knows not the exact time for her pangs; so we also know that the Lord of all will appear, but the moment itself we have by no means been explicitly taught.” The comment, however, hardly suits this passage, as the persons on whom the destruction will thus burst are not persons who live in any expectation of such a judgment.