Isaiah 15: 3-4. “In their streets they shall gird themselves with sackcloth: on the tops of their houses, and in their streets, every one shall howl, weeping abundantly. And Heshbon shall cry, and Elealeh: their voice shall be heard even unto Jahaz: therefore the armed soldiers of Moab shall cry out; his life shall be grievous unto him.”
Sackcloth would be called burlap today. It was used primarily for making bags for such things as harvested grain. Rough and uncomfortable, there was no beauty in it. It was the practice, for someone who was grieving, to wear sackcloth to show the depth of sorrow.
The Moabites, after their utter defeat, would literally be crying in the streets and the housetops.
The cities mentioned in verse four were all part of the destruction, which was complete. No corner escaped the armies of Assyria. In fact, the armed Moabite soldiers that survived would find life not worth living. The shame of their defeat, and the hopelessness of their future, made their lives grievous to them.