נגעים ו׳Negaim 6

Mishnah 3ג׳

בַּהֶרֶת כַּגְּרִיס וּבָהּ מִחְיָה פְחוּתָה מִכָּעֲדָשָׁה, רָבְתָה הַבַּהֶרֶת, טְמֵאָה. נִתְמַעֲטָה, טְהוֹרָה. רָבְתָה הַמִּחְיָה, טְמֵאָה. נִתְמַעֲטָה, רַבִּי מֵאִיר מְטַמֵּא, וַחֲכָמִים מְטַהֲרִים, שֶׁאֵין הַנֶּגַע פּוֹשֶׂה לְתוֹכָהּ:

A Baheret like [the size of] a bean with a patch of healthy skin in it smaller than a lentil, [if] the Baheret spread, it becomes impure. [If] it diminished, it becomes pure. [If] the patch spread, it becomes impure. [If] it diminished, Rabbi Meir declares impure and the Sages declare pure because a Nega [diseased patch on skin, clothes, or houses that create impurity] cannot spread within itself.

Mishnah 4ד׳

בַּהֶרֶת יְתֵרָה מִכַּגְּרִיס וּבָהּ מִחְיָה יְתֵרָה מִכָּעֲדָשָׁה, רַבּוּ אוֹ שֶׁנִּתְמַעֲטוּ, טְמֵאִין, וּבִלְבַד שֶׁלֹּא יִתְמַעֲטוּ מִכַּשִּׁעוּר:

A Baheret more than [the size of] a bean and within it is a patch of healthy skin more than [the size of] a lentil, [if] they grew or diminished, they are [still] impure, as long as they do not diminish to less than the [minimum] area.