Or HaChaim on Deuteronomy 7:7/אור החיים על דברים ז׳:ז׳

1 כי אתם המעט, "for you are the fewest, etc." The Torah could not content itself with writing "not because you were numerous, etc.," as that might have implied that though the Jewish people were not more numerous than other nations they were nonetheless equal to them in number.