This is a litotes that is used to emphasize that the Israelites did not let anyone live. AT: "all of his people were dead" (See: [[rc://en/ta/man/translate/figs-litotes]])
# There was not one of the sixty cities that we did not take
This is a double negative that emphasizes that they took all of the 60 cities. AT: "We took every one of the sixty cities" (See: [[rc://en/ta/man/translate/figs-doublenegatives]])