Halakhah for Negaim 1:3
אַרְבָּעָה מַרְאוֹת הָאֵלּוּ מִצְטָרְפִין זֶה עִם זֶה לִפְטֹר, וּלְהַחְלִיט, וּלְהַסְגִּיר. לְהַסְגִּיר אֶת הָעוֹמֵד בְּסוֹף שָׁבוּעַ רִאשׁוֹן. לִפְטֹר אֶת הָעוֹמֵד בְּסוֹף שָׁבוּעַ שֵׁנִי. לְהַחְלִיט אֶת שֶׁנּוֹלַד לוֹ מִחְיָה אוֹ שֵׂעָר לָבָן, בַּתְּחִלָּה, בְּסוֹף שָׁבוּעַ רִאשׁוֹן, בְּסוֹף שָׁבוּעַ שֵׁנִי, לְאַחַר הַפְּטוּר. לְהַחְלִיט אֶת שֶׁנּוֹלַד לוֹ פִשְׂיוֹן, בְּסוֹף שָׁבוּעַ רִאשׁוֹן, בְּסוֹף שָׁבוּעַ שֵׁנִי, לְאַחַר הַפְּטוּר. לְהַחְלִיט אֶת הַהוֹפֵךְ כֻּלּוֹ לָבָן מִתּוֹךְ הַפְּטוּר. לִפְטֹר אֶת הַהוֹפֵךְ כֻּלּוֹ לָבָן מִתּוֹךְ הֶחְלֵט אוֹ מִתּוֹךְ הֶסְגֵּר. אֵלּוּ מַרְאוֹת נְגָעִים שֶׁכָּל נְגָעִים תְּלוּיִם בָּהֶן:
These four appearances [of <i>Negaim</i>] combine, one with the other, to exempt [one from impurity], to decide [that one is impure], or to quarantine [one of uncertain status]. [They combine] to quarantine that which remains [unchanged] at the end of the first week [from reporting the <i>Nega</i>]. [They combine] to exempt that which remains [unchanged] at the end of the second week. [They combine] to decide that which develops healthy skin [in the area of the <i>Nega</i>] or white hair, [whether] initially, at the end of the first week, at the end of the second week, [or] after the exemption. [They combine] to decide that which develops spreading, [whether] at the end of the first week, at the end of the second week, [or] after the exemption. [They combine] to decide that which turns completely white, [coming] from [the state of] exemption. [They combine] to exempt one who turns completely white, [coming] from [the state of] the decision [that he was impure] or from quarantine. These are the appearances of <i>Negaim</i> which all <i>Negaim</i> are based upon.