This iniquity shall be to you as a breach ready to fall. Your sin in rebelling against God, rejecting the warnings of his prophets, and trusting in your own devices shall bring you into the condition of a wall in which there is a "breach," or rather, a "bulge," which therefore totters to its fall, and is liable to dissolve in ruins at any moment.
Swelling out in a high wall. The higher the wail, the greater the danger, and the more complete the destruction.