Jamieson, Fausset and Brown on Isaiah 15:5

5. My--The prophet himself is moved with pity for Moab. Ministers, in denouncing the wrath of God against sinners, should do it with tender sorrow, not with exultation.

fugitives--fleeing from Moab, wander as far as to Zoar, on the extreme boundary south of the Dead Sea. Horsley translates, "her nobility," or "rulers" (Ho 4:18).

heifer, &c.--that is, raising their voices "like a heifer" (compare Jr 48:34, 36). The expression "three years old," implies one at its full vigor (Ge 15:9), as yet not brought under the yoke; as Moab heretofore unsubdued, but now about to be broken. So Jr 31:18; Ho 4:13. Maurer translates, "Eglath" (in English Version, "a heifer") Shelishijah (that is, the third, to distinguish it from two others of the same name).

by the mounting up--up the ascent.

Luhith--a mountain in Moab.

Horonaim--a town of Moab not far from Zoar (Jr 48:5). It means "the two poles," being near caves.

cry of destruction--a cry appropriate to the destruction which visits their country.