Mishnah for Kelim 24:17
שָׁלֹשׁ קֻפּוֹת הֵן. מְהוּהָה שֶׁטְּלָיָהּ עַל הַבְּרִיָּה, הוֹלְכִין אַחַר הַבְּרִיָּה. קְטַנָּה עַל הַגְּדוֹלָה, הוֹלְכִין אַחַר הַגְּדוֹלָה. הָיוּ שָׁווֹת, הוֹלְכִין אַחַר הַפְּנִימִית. רַבִּי שִׁמְעוֹן אוֹמֵר, כַּף מֹאזְנַיִם שֶׁטְּלָיָהּ עַל שׁוּלֵי הַמֵּחַם, מִבִּפְנִים, טָמֵא. מִבַּחוּץ, טָהוֹר. טְלָיָהּ עַל צִדָּהּ, בֵּין מִבִּפְנִים בֵּין מִבַּחוּץ, טָהוֹר:
There are three different types of containers: a worn-out basket which one patched onto a sound one follows after [the purity status of] the sound one; a small one [patched] onto a large follows after [the purity status] the large one; those [baskets, patched onto each another] which are equal [in size] follow after the inner one. Rabbi Shimon says: Regarding an [impure] cup of a scale which one patched onto the bottom of a boiler, if [it was patched] from the inside, it [i.e. even the boiler] is impure; if from the outside, it is pure; if one patched it from the side, whether on the inside or on the outside, it is pure.