Revelation 9:13-16
And the sixth angel sounded, and (1) I heard a voice from the four horns of the golden altar which is before God one saying to the sixth angel who had the trumpet, (2) "release the four angels who are bound at the great river Euphrates. "And the four angels, who had been prepared for the hour and day and month and year, were released, so that they might kill a third of mankind.And the number of the armies of the horsemen was two hundred million; I heard the number of them.