Give glory to the Lord— That is to say, "Confess your faults, and humble yourselves under his mighty hand, before he bring upon you the night of affliction; before the time come, when ye shall be forced to fly by night unto the mountains for fear of the enemy." See Calmet.
The dark mountains— The mountains of gloominess. By ףּנשׁ הרי harei nasheph, I imagine those caverns and holes in the mountains are meant, which the Jews were wont to make use of for burying-places; the gloomy shade of which probably gave rise to that expression which we meet with both here and elsewhere, "the shadow of death." The prophet Isaiah makes use of much the same images, Isaiah 59:9-10.