Parashas Metzora · Passuk 15:03
Chabad.org — English translation + Rashi
Torah Temima points to Niddah 43b (verified on the daf).
E-Daf.com — Tsurras Hadaf (size=3)
HebrewBooks / Shas PDF of the daf
English: “His flesh runs” — “his discharge” is one, “his flesh runs” is two, “his discharge” [again] is three; this teaches that a zav of three sightings is obligated to bring an offering.
Three sightings for the korban
Chazal derive from the multiple expressions that three separate emissions obligate the zav to bring a korban.