In Ramban's commentary on the parsha קְדֹשִׁים תִּהְיוּ... However, as I have indicated, the call for further strictness can hardly be derived from the Torah text. We read in Josephus' book on the Romans that during the Second Temple there were people [ESB: The Essenes] who withdrew to the wilderness where they lived as hermits restricting their nourishment to the fruit growing on trees and abstained from all worldly enterprise. The Sages, however, denounced such behavior. Indeed, those who worship God perfectly must in their conduct please both God and their fellow beings rather than renouncing the accepted social and civic norms, because widespread withdrawal undermines the natural order, ruins civilization and destroys the fabric of our nation.
This is the meaning of the Rabbinic dictum, "well-founded is the Torah in conjunction with worldly occupation." Hence, all individual abstention must accord with the capacity of the entire nation. On the other hand, any regimen restricted to the individual, which overburdens the nation as a whole, actually contradicts perfection. Accordingly, such practice was frowned upon by the Jewish Sages. This is the meaning of the Midrash, "This parsha was delivered בהקהל, in full assembly," i.e. all holiness that renounces the permitted must be in consonance with what can be tolerated by those gathered in "full assembly."