TT #287 · Parshas Tazria · Aliyah 7 · Passuk 54
English: The priest shall command that they wash the article in which the lesion is found, and he shall isolate it another seven days.
Yerushalmi Shabbos 2:1.
Sefaria — Jerusalem Talmud Shabbos 2:1 · Yerushalmi Shabbos 15b (Wikisource)
English: Why is the second washing required? Just as the first washing must be intentional, so must the second. And how do we know that the first washing must be intentional? Scripture says, “The priest shall command, and they shall wash”—that is, by deliberate action.
Textual derivation
The required washing is an intentional act, not an accidental or automatic result.