Midrash sur Le Lévitique 13:33

4) (Vayikra 13:33) ("Then he shall be shaved, but the nethek he shall not shave. And the Cohein shall quarantine the nethek a second seven days.") "Then he shall be shaved": by any man (and not necessarily a Cohein). Because we find the last shaving (on the day of his cleansing [Vayikra 14:9] to be by a Cohein, I might think that this, too, must be by a Cohein; it is, therefore, written "Then he shall be shaved" — by any man.

5) "Then he shall be shaved": by any man. Because we find the last shaving to be by a razor. I might think that this, too, must be by a razor; it is, therefore, written "Then he shall be shaved" — by any instrument.

6) "Then he shall be shaved": even if he is a Nazirite. Because it is written (of a Nazirite, Bamidbar 6:5) "a razor shall not pass over his head," I might think even if he was afflicted (with leprosy); it is, therefore, written "Then he shall be shaved" — even if he was afflicted.