Mishnah Negaim 3:3: Skin of the flesh [that has a Nega] is made impure after two weeks or through three signs: white hair, a healed patch [of skin], or expansion. Regarding white hair and a healed patch, [they cause impurity] initially, at the end of the first week [of quarantine], at the end of the second week, or after the exemption. Regarding expansion, at the end of the first week, at the end of the second week, or after the exemption. And it is made impure after two weeks, which are [actually] thirteen days.

עוֹר הַבָּשָׂר מִטַּמֵּא בִשְׁנֵי שָׁבוּעוֹת וּבִשְׁלשָׁה סִימָנִין, בְּשֵׂעָר לָבָן וּבְמִחְיָה וּבְפִסְיוֹן. בְּשֵׂעָר לָבָן וּבְמִחְיָה, בַּתְּחִלָּה, וּבְסוֹף שָׁבוּעַ רִאשׁוֹן, וּבְסוֹף שָׁבוּעַ שֵׁנִי, לְאַחַר הַפְּטוּר. וּבְפִסְיוֹן, בְּסוֹף שָׁבוּעַ רִאשׁוֹן, וּבְסוֹף שָׁבוּעַ שֵׁנִי, לְאַחַר הַפְּטוּר. וּמִטַּמֵּא בִשְׁנֵי שָׁבוּעוֹת, שֶׁהֵן שְׁלשָׁה עָשָׂר יוֹם:

Mishnah Negaim 3:4: [A Nega in the area of] a boil or a burn is made impure after a week or through two signs: white hair or expansion. Regarding white hair, [it causes impurity] initially, at the end of the week [of quarantine], or after the exemption. Regarding expansion, at the end of the week [or] after the exemption. And they are made impure after one week, which is seven days.

הַשְּׁחִין וְהַמִּכְוָה מִטַּמְּאִין בְּשָׁבוּעַ אֶחָד וּבִשְׁנֵי סִימָנִין, בְּשֵׂעָר לָבָן וּבְפִסְיוֹן. בְּשֵׂעָר לָבָן, בַּתְּחִלָּה, בְּסוֹף שָׁבוּעַ, לְאַחַר הַפְּטוּר. וּבְפִסְיוֹן, בְּסוֹף שָׁבוּעַ, לְאַחַר הַפְּטוּר. וּמִטַּמְּאִין בְּשָׁבוּעַ אֶחָד, שֶׁהוּא שִׁבְעַת יָמִים: