אור החיים — טהור הוא וטהרו הכהן

Q — Why the apparent redundancy of 'טהור הוא וטהרו הכהן' ('he is pure, and the kohen shall pronounce him pure') — wouldn't either phrase suffice? The Sifra reports Hillel ascended from Bavel over this very verse.

A — Or HaChaim notes that Hillel's reading prevailed only because it matched the received halacha — it is not the sole possible reading. He reconstructs how Hillel's opponents read it: 'טהור הוא' alone might mean that if the person himself recognizes his condition is clear, he may leave without the kohen; the addition 'וטהרו הכהן' teaches he may not depart until the kohen declares 'you are pure.' Hillel could not compel his reading from the verse alone until he came to Eretz Yisrael and learned that the halacha indeed accords with his interpretation.