In a dream, in a {g} vision of the night, when deep sleep falleth upon men, in slumberings upon the bed;

(g) God, he says, speaks commonly, either by visions to teach us the cause of his judgments, of else by affliction or by his messenger.

Jamieson-Fausset-Brown Bible Commentary

15. slumberings-light is opposed to "deep sleep." Elihu has in view Eliphaz (Job 4:13), and also Job himself (Job 7:14). "Dreams" in sleep, and "visions" of actual apparitions, were among the ways whereby God then spake to man (Ge 20:3).

Matthew Henry's Concise Commentary

33:14-18 God speaks to us by conscience, by providences, and by ministers; of all these Elihu discourses. There was not then, that we know of, any Divine revelation in writing, though now it is our principal guide. When God designs men's good, by the convictions and dictates of their own consciences, he opens the heart, as Lydia's, and opens the ears, so that conviction finds or forces its way in. The end and design of these admonitions are to keep men from sin, particularly the sin of pride. While sinners are pursuing evil purposes, and indulging their pride, their souls are hastening to destruction. That which turns men from sin, saves them from hell. What a mercy it is to be under the restraints of an awakened conscience!