Keilim27: 3
הָעוֹשֶׂה שְׁנַיִם מִן הַבֶּגֶד וְאֶחָד מִן הַשַּׂק, שְׁלָשְׁתָּן מִן הַשַּׂק וְאֶחָד מִן הָעוֹר, אַרְבָּעָה מִן הָעוֹר וְאֶחָד מִן הַמַּפָּץ — טָהוֹר. חֲמִשָּׁה מִן הַמַּפָּץ וְאֶחָד מִן הָעוֹר, אַרְבָּעָה מִן הָעוֹר וְאֶחָד מִן הַשַּׂק, שְׁלשָׁה מִן הַשַּׂק וְאֶחָד מִן הַבֶּגֶד — טָמֵא. זֶה הַכְּלָל: כֹּל שֶׁחִבֵּר לוֹ מִן הֶחָמוּר מִמֶּנּוּ — טָמֵא; מִן הַקַּל מִמֶּנּוּ — טָהוֹר.
[If] one made [a piece of material with] two [handbreadths] of cloth and one [handbreadth] of sack, three [handbreadths] of sack and one [handbreadth] of hide, [or] four [handbreadths] of hide and one [handbreadth] of matting, it is tahor. [But if he made a piece of material with] five [handbreadths] of matting and one [handbreadth] of hide, four [handbreadths] of hide and one [hand- breadth] of sack, [or] three [handbreadths] of sack and one [handbreadth] of cloth, it is tamei. This is the rule: Whatever has [a different material] attached to it; [if it is] from a [material] more stringent than it, it is tamei; [if it is] from a [material] less stringent than it, it is tahor.