Extra Credit · Parallel Chazal
English: The priest shall examine the netek on the seventh day; if the netek has not spread in the skin and its appearance is not deeper than the skin, the priest shall declare him clean; he shall wash his garments and be clean.
Chabad.org — Rashi for Vayikra 13:34
Sifra (Toras Kohanim), Tazria, Parashat Nega'im 9:8 (Vayikra 13:34)
English: “He shall wash his garments”—he no longer transmits impurity through bedding and seating or through entry into a house. “And he shall be clean”—he is released from the requirements of letting his hair grow, tearing his garments, shaving, and bringing birds. “He shall wash his garments”—this includes immersion. Could he then be fully released? Scripture says, “If it spreads further, he is impure.”
The Sifra explains what washing accomplishes and adds that immersion is required. The process is not irrevocably closed: renewed spread can still restore the person’s impure status.