Albert Barnes Commentary Psalms 83:10

"Who perished at Endor, Who became as dung for the earth." — Psalms 83:10 (ASV)

Which perished at En-dor - Endor is not particularly mentioned in the historical account in the book of Judges, but it is known that Endor was in the vicinity of Mount Tabor, and there is no improbability in the tradition that has fixed the site of the battle at or near Endor. The word or name “En-dor” properly means spring of the dwelling (or, habitation), and was probably given at first to a spring or fountain near which some distinguished or well-known person lived. It is mentioned in Joshua 17:11 and 1 Samuel 28:7.

They became as dung for the earth - The land was enriched or made fertile by their flesh, their blood, and their bones, just as the field of Waterloo was by those slain, or as battlefields commonly are.