Jamieson, Fausset and Brown on Luke 17:34

34. two in one bed--the prepared and unprepared mingled in closest intercourse together in the ordinary walks and fellowships of life, when the moment of severance arrives. Awful truth! realized before the destruction of Jerusalem, when the Christians found themselves forced by their Lord's directions (Lu 21:21) at once and for ever away from their old associates; but most of all when the second coming of Christ shall burst upon a heedless world.