הַמַּפָּץ הוּא הַמַּחְצֶלֶת שֶׁאוֹרְגִין אוֹתָהּ מִן הַחֲבָלִים וּמִן הַסּוּף וּמִן הַגֹּמֶא וְכַיּוֹצֵא בָּהֶן. וְאֵין הַמַּפָּץ בִּכְלַל כֵּלִים הָאֲמוּרִין בַּתּוֹרָה וְאַף עַל פִּי כֵן מִתְטַמֵּא הוּא בְּמִדְרָס דִּין תּוֹרָה שֶׁהֲרֵי רִבָּה הַכָּתוּב (ויקרא טו ד) "כָּל הַמִּשְׁכָּב" וְזֶה רָאוּי לְמִשְׁכָּב וְעָשׂוּי לוֹ. וְכֵן מִתְטַמֵּא בְּמֵת וּבִשְׁאָר טֻמְאוֹת מִדִּבְרֵיהֶן כְּכָל פְּשׁוּטֵי כְּלֵי עֵץ כְּמוֹ שֶׁבֵּאַרְנוּ. וְזֶה כְּלָל גָּדוֹל שֶׁכָּל הַמִּתְטַמֵּא בְּמִדְרָס מִתְטַמֵּא בִּשְׁאָר טֻמְאוֹת:
A mapatz is a mat made by interweaving cords, reeds, grasses, or the like. A mapatz is not one of the keiliim mentioned by the Torah. Nevertheless, it is susceptible to the impurity associated with the support of a zav according to Scriptural Law. The rationale is that Leviticus 15:4 states "All surfaces on which one lies," expanding the category of articles susceptible to impurity. A mat is thus included, because it is fit to lie on and is indeed made for that purpose. Similarly, it contracts impurity from contact with a human corpse and other sources of impurity according to Rabbinic Law, like all other flat wooden keiliim, as we explained. This is a great general principle: Any entity that is susceptible to the impurity associated with the support of a zav is susceptible to other types of impurity.
