Reference for Kelim 18:7
כֶּרַע שֶׁהָיְתָה טְמֵאָה מִדְרָס, וְחִבְּרָהּ לַמִּטָּה, כֻּלָּהּ טְמֵאָה מִדְרָס. פֵּרְשָׁה, הִיא טְמֵאָה מִדְרָס, וְהַמִּטָּה מַגַּע מִדְרָס. הָיְתָה טְמֵאָה טֻמְאַת שִׁבְעָה וְחִבְּרָהּ לַמִּטָּה, כֻּלָּהּ טְמֵאָה טֻמְאַת שִׁבְעָה. פֵּרְשָׁה, הִיא טְמֵאָה טֻמְאַת שִׁבְעָה, וְהַמִּטָּה טְמֵאָה טֻמְאַת עָרֶב. הָיְתָה טְמֵאָה טֻמְאַת עֶרֶב וְחִבְּרָהּ לַמִּטָּה, כֻּלָּהּ טְמֵאָה טֻמְאַת עָרֶב. פֵּרְשָׁה, הִיא טְמֵאָה טֻמְאַת עֶרֶב, וְהַמִּטָּה טְהוֹרָה. וְכֵן הַשֵּׁן שֶׁל מַעְדֵּר:
If a [bed] leg that had contracted <em>midras</em> impurity is attached to a bed, all the bed contracts <em>midras</em> impurity. If he removed [the leg], it retains its <em>midras</em> impurity, while the bed is [impure due to] contact with [an object impure through] <em>midras</em>. If a bed leg that was subject to a seven-day impurity [through exposure to a corpse] was joined to a bed, all the bed contracts seven-day impurity. If he removed it, it retains its seven-day impurity, while the bed is only subject to evening impurity. If a leg that was subject to evening impurity was joined to a bed, all the bed contracts evening impurity. If he subsequently removed it, it is still subject to evening impurity, and the bed becomes pure. The same law applies also to the prong of a mattock.