Reference for Shabbat 21:3
בֵּית שַׁמַּאי אוֹמְרִים, מַגְבִּיהִין מִן הַשֻּׁלְחָן עֲצָמוֹת וּקְלִפִּין. וּבֵית הִלֵּל אוֹמְרִים, נוֹטֵל אֶת הַטַּבְלָה כֻלָּהּ וּמְנַעֲרָהּ. מַעֲבִירִין מִלִּפְנֵי הַשֻּׁלְחָן פֵּרוּרִין פָּחוֹת מִכַּזַּיִת וְשֵׂעָר שֶׁל אֲפוּנִין וְשֵׂעָר שֶׁל עֲדָשִׁים, מִפְּנֵי שֶׁהוּא מַאֲכַל בְּהֵמָה. סְפוֹג, אִם יֶשׁ לוֹ עוֹר בֵּית אֲחִיזָה, מְקַנְּחִין בּוֹ, וְאִם לָאו, אֵין מְקַנְּחִין בּוֹ. וַחֲכָמִים אוֹמְרִים בֵּין כָּךְ וּבֵין כָּךְ, נִטָּל בְּשַׁבָּת, וְאֵינוֹ מְקַבֵּל טֻמְאָה:
Beth Shammai say: It is permitted to lift bones and shells from the table (on Shabbath). Beth Hillel say: He takes the entire tablecloth and shakes it out. [The gemara explains that we do not rely upon our Mishnah as stated, but reverse it, viz.: "Beth Hillel say: It is permitted … and Beth Shammai say: He takes the entire tablecloth, etc.", for it (the tablecloth) has the status of a (movable) article. But he may not take the bones and the shells with his hands. For Beth Hillel hold with R. Shimon; and Beth Shammai, with R. Yehudah. However, Beth Hillel permit it only with bones and shells that are fit to be eaten by animals though not fit to be eaten by men; but if they are not fit to be eaten by animals either, Beth Hillel concur that it is forbidden to handle them, for in such an instance, even R. Shimon concurs.] It is permitted to remove crumbs [even] less than the size of an olive from the table, and bean shells, and lentil shells, for they are animal food. A sponge — if it has a leather handle, one may clean with it; if not, one may not clean with it. [For when he holds it, it is squeezed by his fingers, and it is inevitable (that water be squeezed out), in which instance R. Shimon concedes (that it is forbidden)]. And the sages say: In either case, [whether or not it has a handle], it may be taken on Shabbath [when it is dry], and it does not acquire uncleanliness, [for it is neither a wooden vessel, nor cloth, nor sack, nor metal].