Parashas Metzora · Passuk 14:05
Chabad.org — English translation + Rashi
Torah Temima points to Sotah 15b (verified on the daf).
E-Daf.com — Tsurras Hadaf (size=3)
HebrewBooks / Shas PDF of the daf
English: “An earthenware vessel over living water” — just as living water has never been used for work, so the vessel must never have been used for work.
Heqesh
Chazal derive from the parallel that the earthenware vessel must be new and unused.