Isaiah 18:3

See ye; take notice of what I say and God will do. Or, ye shall see it; you shall be eye-witnesses of this dreadful woe or judgment which I am bringing upon the people of whom I have spoken: The prophet doth in a manner summon all nations to bear witness of his prophecy, and of the accomplishment thereof. When he lifteth up an ensign on the mountains, and when he bloweth a trumpet; when God shall gather together the nations, as it were, by the lifting up of an ensign, or by the sound of a trumpet, to execute his judgments upon this people. Heb. as when a man lifts up an ensign upon the mountains, which men can easily see; and as when a man sounds a trumpet, they can hear: no less visible and manifest shall this judgment of God be. Hear ye; ye shall hear it, as in the other branch.