נגעים י״בNegaim 12

Mishnah 1א׳

כָּל הַבָּתִּים מִטַּמְּאִין בַּנְּגָעִים, חוּץ מִשֶּׁל נָכְרִים. הַלּוֹקֵחַ בָּתִּים מִן הַנָּכְרִים, יֵרָאוּ בַתְּחִלָּה. בַּיִת עָגֹל, בַּיִת טְרִיגוֹן, בַּיִת הַבָּנוּי בִּסְפִינָה אוֹ בְאַסְקַרְיָא, עַל אַרְבַּע קוֹרוֹת, אֵינוֹ מִטַּמֵּא בַנְּגָעִים. וְאִם הָיָה מְרֻבָּע, אֲפִלּוּ עַל אַרְבָּעָה עַמּוּדִים, מִטַּמֵּא:

All houses become impure from Negaim [diseased patches on skin, clothes, or houses that create impurity] except those of non-Jews. One who buys houses from non-Jews should examine them as if in the beginning [of the Nega]. A round house, a triangular house, or a house built on a ship or on a mast or on four beams, does not become impure from Negaim. If it were square, even if it were on four pillars, it would be able to become impure.

Mishnah 2ב׳

בַּיִת שֶׁאַחַד מִצְּדָדָיו מְחֻפֶּה בְשַׁיִשׁ, אֶחָד בְּסֶלַע, וְאֶחָד בִּלְבֵנִים, וְאֶחָד בְּעָפָר, טָהוֹר. בַּיִת שֶׁלֹּא הָיוּ בוֹ אֲבָנִים וְעֵצִים וְעָפָר וְנִרְאָה בוֹ נֶגַע וְאַחַר כָּךְ הֵבִיאוּ בוֹ אֲבָנִים וְעֵצִים וְעָפָר, טָהוֹר. וְכֵן בֶּגֶד שֶׁלֹּא אָרַג בּוֹ שָׁלשׁ עַל שָׁלשׁ וְנִרְאָה בוֹ נֶגַע וְאַחַר כָּךְ אָרַג בּוֹ שָׁלשׁ עַל שָׁלשׁ, טָהוֹר. אֵין הַבַּיִת מִטַּמֵּא בַנְּגָעִים עַד שֶׁיְּהֵא בוֹ אֲבָנִים וְעֵצִים וְעָפָר:

A house that one of its sides is covered in marble, one with rocks, one with bricks and one with dirt is pure. A house that did not have in it stones, wood or dirt and a Nega appeared in it and later they brought into it stones, wood or dirt, it is pure. Similarly a piece of clothing that was not woven [an area of] three by three [fingers], and a Nega appeared on it, and later it was woven to three by three, it is pure. A house does not become impure from Negaim until it has bricks, woods and dirt.