Mishnah Negaim 6:5: A Baheret like [the size of] a bean with a patch of healthy skin like [the size of] a lentil surrounding it and outside of the patch is [another] Baheret, the inner [Nega] requires quarantine and the outer one is decided [to be impure]. Rabbi Yossi said: The patch is not a sign of impurity for the outer one [and so the outer one also requires quarantine]. [If the patch] diminished or went away, Rabban Gamliel says: If it was disappearing from the inside [edge], it is a sign of expansion for the inner [Nega and therefore it is impure] but the outer one is pure. But if it was from the outside [edge], the outer one is pure and the inner one requires quarantine. Rabbi Akiva says: In both cases [the inner Nega] is pure.

בַּהֶרֶת כַּגְּרִיס וּמִחְיָה כָּעֲדָשָׁה מַקַּפְתָּהּ וְחוּץ לַמִּחְיָה בַּהֶרֶת, הַפְּנִימִית לְהַסְגִּיר, וְהַחִיצוֹנָה לְהַחְלִיט. אָמַר רַבִּי יוֹסֵי, אֵין הַמִּחְיָה סִימַן טֻמְאָה לַחִיצוֹנָה, שֶׁהַבַּהֶרֶת לְתוֹכָהּ. נִתְמַעֲטָה וְהָלְכָה לָהּ, רַבָּן גַּמְלִיאֵל אוֹמֵר, אִם מִבִּפְנִים הִיא כָלָה, סִימַן פִּשְׂיוֹן לַפְּנִימִית, וְהַחִיצוֹנָה טְהוֹרָה. וְאִם מִבַּחוּץ, הַחִיצוֹנָה טְהוֹרָה וְהַפְּנִימִית לְהַסְגִּיר. רַבִּי עֲקִיבָא אוֹמֵר, בֵּין כָּךְ וּבֵין כָּךְ, טְהוֹרָה:

Mishnah Negaim 6:6: Rabbi Shimon said: When [is the law about the patch diminishing on the inner edge true]? When [the patch] is exactly [the area of] a lentil. If it was more than a lentil, the leftover [becomes] the expansion for the inner [Nega] and the outer one is [still] impure. [If instead of a healthy patch] it was a dull patch less than [the area of] a lentil, it is a sign of expansion for the inner [Nega if the inner edge diminished] but is not a sign of expansion for the outer one [if the outer edge diminished] .

אָמַר רַבִּי שִׁמְעוֹן, אֵימָתַי, בִּזְמַן שֶׁהִיא כָעֲדָשָׁה מוּבֵאת. הָיְתָה יְתֵרָה מִכָּעֲדָשָׁה, הַמּוֹתָר סִימַן פִּשְׂיוֹן לַפְּנִימִית, וְהַחִיצוֹנָה טְמֵאָה. הָיָה בֹהַק פָּחוּת מִכָּעֲדָשָׁה, סִימַן פִּשְׂיוֹן לַפְּנִימִית, וְאֵין סִימַן פִּשְׂיוֹן לַחִיצוֹנָה: