If I find in Sodom fifty righteous within the city
Sodom is particularly mentioned because Lot dwelt there, and being the metropolis, and the city of greatest note, as Jarchi observes, it is put for the rest; and the sense is, if fifty righteous persons could be found in all the five cities, mercy should be shown them: then will I spare all the place for their sakes;
not Sodom only, but the whole country, of which Sodom was the chief; the Lord takes up and agrees to the number Abraham pitched upon, and grants the request he makes.