15. I will destroy all My foes.
mountains—in Palestine usually planted with vines and olives in terraces, up to their tops.
islands—rather, "dry lands." God will destroy His foes, the heathen, and their idols, and "dry up" the fountains of their oracles, their doctrines and institutions, the symbol of which is water, and their schools which promoted idolatry [Vitringa].