Parashas Metzora · Passuk 14:57
Chabad.org — English translation + Rashi
Torah Temima points to Toras Kohanim.
English: “To teach” — this teaches that the kohen does not inspect the negaim until his teacher has instructed him.
Requirement of received instruction
Chazal require that the kohen’s authority to inspect and rule on negaim rest on received instruction from his teacher, not on self-taught expertise alone.