俱舍論記 3.36

3.36

「出小便處至起此樂故」者，此破小便處。出小便處於生婬欲樂事不應立根，即女、男根能起此樂，何須計處別立為根？

Regarding "The urinary organ... because of giving rise to this pleasure": this refutes the urinary organ. For the matter of generating sexual pleasure, the urinary organ should not be established as a faculty, because it is precisely the female and male faculties that can give rise to this pleasure; why is it necessary to posit the organ and separately establish it as a faculty?