Mishnah Negaim 1:6: How [is waiting until after Shabbat considered] a stringency? [If] he did not have in [the Nega] white hair [on Shabbat] and [after Shabbat] white hair grew in it, [or if] there were black [hairs] and they whitened, [or if] one was black and one was white and the two of them whitened, [or if the hairs were] short and they were lengthened, [or if there were] one long and one short, and the two of them were lengthened, [or if on Shabbat] a boil encroached upon the two of them or upon one of them, [or if] a boil surrounded the two of them or one of them, or divided them - [this refers to] a boil, a partly-healed boil, a burn, a partly-healed burn, or a Bohak - and went away [after Shabbat]. [Other cases of leniency include if the skin] did not have a healed part and then grew a healed part, [or if the area of the Nega] was circular or stretched and became square, [or if a healed part of skin] had from the side [a Nega] and then became surrounded, [or if the healed part of skin] was scattered and then became concentrated, [or if] a boil came and went into [the healed part of the skin], surrounded it, split it, or diminished it - [this refers to] a boil, a partly-healed boil, a burn, a partly-healed burn, or a Bohak - and went away [after Shabbat], [or if the Nega] did not have an extension and then grew an extension, [or if a] boil, a partly-healed boil, a burn, a partly-healed burn, or a Bohak separate between the original and its expansion and went away [after Shabbat]. These are [cases in which waiting until after Shabbat is considered a] stringency.

כֵּיצַד לְהַחְמִיר. לֹא הָיָה בוֹ שֵׂעָר לָבָן וְנוֹלַד לוֹ שֵׂעָר לָבָן, הָיוּ שְׁחוֹרוֹת וְהִלְבִּינוּ, אַחַת שְׁחוֹרָה וְאַחַת לְבָנָה וְהִלְבִּינוּ שְׁתֵּיהֶן, קְצָרוֹת וְהֶאֱרִיכוּ, אַחַת קְצָרָה וְאַחַת אֲרֻכָּה וְהֶאֱרִיכוּ שְׁתֵּיהֶן, נִסְמַךְ הַשְּׁחִין לִשְׁתֵּיהֶן אוֹ לְאַחַת מֵהֶן, הִקִּיף הַשְּׁחִין אֶת שְׁתֵּיהֶן אוֹ אֶת אַחַת מֵהֶן, אוֹ חִלְּקוֹ הַשְּׁחִין וּמִחְיַת הַשְּׁחִין וְהַמִּכְוָה וּמִחְיַת הַמִּכְוָה וְהַבֹּהַק וְהָלְכוּ לָהֶם, לֹא הָיְתָה בוֹ מִחְיָה וְנוֹלְדָה לוֹ מִחְיָה, הָיְתָה עֲגֻלָּה אוֹ אֲרֻכָּה וְנַעֲשֵׂית מְרֻבַּעַת, מִן הַצַּד וְנַעֲשֵׂית מְבֻצֶּרֶת, מְפֻזֶּרֶת וְנִתְכַּנְּסָה וּבָא הַשְּׁחִין וְנִכְנַס בְּתוֹכָהּ, הִקִּיפָהּ, חִלְּקָהּ, אוֹ מִעֲטָהּ הַשְּׁחִין אוֹ מִחְיַת הַשְּׁחִין וְהַמִּכְוָה וּמִחְיַת הַמִּכְוָה וְהַבֹּהַק וְהָלְכוּ לָהֶן, לֹא הָיָה בוֹ פִסְיוֹן וְנוֹלַד בּוֹ פִסְיוֹן, הַשְּׁחִין וּמִחְיַת הַשְּׁחִין וְהַמִּכְוָה וּמִחְיַת הַמִּכְוָה וְהַבֹּהַק חוֹלְקִין בֵּין הָאוֹם לַפִּסְיוֹן וְהָלְכוּ לָהֶן, הֲרֵי אֵלּוּ לְהַחְמִיר:

Mishnah Negaim 2:1: A bright Baheret [type of diseased patch that creates impurity] looks dull on a light-skinned person [lit. German] and a dull one looks bright on a dark-skinned person [lit. Ethiopian]. Rabbi Yishmael says: Bnei Yisrael, may I am be their atonement, behold they are like box-wood, not black and not white, but intermediate. Rabbi Akiva says: Painters have pigments with which they paint forms black or white or intermediate. One brings an intermediate pigment and surrounds it [the Nega] from outside, and it will appear in the intermediate. Rabbi Yehudah says: The appearances of Negaim [diseased patches on skin, clothes, or houses that create impurity, should be decided] for leniency [when in doubt] but not for stringency: he [the examining priest] should look at the light-skinned person in [comparison with] his skin for leniency and the dark-skinned person in [comparison with] intermediate [dye] for leniency. The Sages say: Both this and this [case should be looked at in comparison with] intermediate [dye].

בַּהֶרֶת עַזָּה נִרְאֵית בַּגֶּרְמָנִי כֵּהָה, וְהַכֵּהָה בַכּוּשִׁי עַזָּה. רַבִּי יִשְׁמָעֵאל אוֹמֵר, בְּנֵי יִשְׂרָאֵל, אֲנִי כַפָּרָתָן, הֲרֵי הֵן כְּאֶשְׁכְּרוֹעַ, לֹא שְׁחוֹרִים וְלֹא לְבָנִים, אֶלָּא בֵינוֹנִיִּים. רַבִּי עֲקִיבָא אוֹמֵר, יֵשׁ לַצַּיָּרִים סַמְמָנִין שֶׁהֵן צָרִין צוּרוֹת שְׁחוֹרוֹת, לְבָנוֹת וּבֵינוֹנִיּוֹת. מֵבִיא סַם בֵּינוֹנִי וּמַקִּיפוֹ מִבַּחוּץ, וְתֵרָאֶה בַבֵּינוֹנִי. רַבִּי יְהוּדָה אוֹמֵר, מַרְאוֹת נְגָעִים לְהָקֵל אֲבָל לֹא לְהַחְמִיר, יֵרָאֶה הַגֶּרְמָנִי בִּבְשָׂרוֹ לְהָקֵל, וְהַכּוּשִׁי בַּבֵּינוֹנִי לְהָקֵל. וַחֲכָמִים אוֹמְרִים, זֶה וָזֶה בַּבֵּינוֹנִי: