John Calvin on Isaiah 15:4

4. And Heshbon shall cry, and Elealeh. Here he names other cities; for his design is to bind up, as it were, in a bundle all the cities of that country, that they may be involved in the general destruction; as if he had said, that none at all shall be exempted.

Therefore the light-armed soldiers of Moab shall howl. Though על כן (gnal ken) literally signifies therefore, yet some think that a reason is not here assigned; but that is of little importance. The Prophet shows that there will be none that does not howl; for he declares that the bold and courageous shall mourn. Next he adds, the soul of every one shall howl to him. {Bogus footnote} Every one shall be so engrossed with his own grief, that he will not think of his neighbors.