Parashas Metzora · Passuk 15:33
Chabad.org — English translation + Rashi
Torah Temima points to Toras Kohanim.
English: “For the male and for the female” — for the third sighting he is equated to the female: just as a female becomes impure under duress, so a male on the third sighting becomes impure under duress.
Third sighting even under ones
Once two prior sightings have established zivah susceptibility, the third sighting conveys impurity even if forced — paralleling the female zavah.