These verses are rightly taken together. The figure occurs in Isaiah 10:17-18 (comp. Zechariah 12:6), but there as a metaphor; here as a simile. “Before the rains came the whole mountain side was in a blaze. Thorns and briars grow so luxuriantly here that they must be burned off always before the plough can operate. The peasants watch for a high wind, and then the fire catches easily, and spreads with great rapidity” (Thomson, Land and Book, p. 341). The mountains are pre-eminently the pastures. (Comp. Psalms 50:10; Psalms 147:8.)
Related Commentaries of Psalms 83:14
Psalms 83:14-15
14 As the fire burneth a wood, and as the flame setteth the mountains on fire;
15 So persecute them with thy tempest, and make them afraid with thy storm.