John Gill Commentary 2 Kings 3:25

"And they beat down the cities; and on every good piece of land they cast every man his stone, and filled it; and they stopped all the fountains of water, and felled all the good trees, until in Kir-hareseth [only] they left the stones thereof; howbeit the slingers went about it, and smote it." — 2 Kings 3:25 (ASV)

And they beat down the cities
Demolished the walls of them, and houses in them, wherever they came:

and on every good piece of land cast every man his stone, and filled
it ;
which they had taken out of the walls and houses they pulled down; or which they picked up in the highway, as they passed along, being a stony country; or which being laid in heaps, gathered out of the fields, they took and scattered them all over them:

and they stopped all the wells of water ;
with stones and dirt:

and felled all the good trees ;
fruit bearing ones; (See Gill on 2 Kings 3:19),

only in Kirharaseth left they the stones thereof ;
not able to demolish it, it being a strong fortified city, the principal of the kingdom, and into which the king of Moab had thrown himself, and the remains of his forces; of which see (Isaiah 16:7Isaiah 16:10) ,

howbeit, the slingers went about it, and smote it ;
smote the soldiers that appeared upon the walls of it; though Kimchi, and other Jewish writers, understand it of engineers, who cast out large stones from a sort of machines then in use, to batter down and break through the walls of cities.