Laundering a garment with water on Shabbat constitutes a Torah violation. The question, however, arises, is it permissible to remove dirt from a garment without using water, such as by scraping dirt with one's fingernail, or by shaking or lightly rubbing the material?
The Shulhan Aruch (302:7; listen to audio for precise citation) addresses the issue of scraping dirt from the garment with one's fingernail, and rules that this is permissible on Shabbat. He then proceeds to cite an opposing view which rules stringently in this regard, allowing scraping dirt from a material only if the dirt is moist. If the dirt is dry, this view contends, scraping it would constitute a form of grinding which is forbidden on Shabbat. (Although this kind of "grinding" would not transgress the Biblical prohibition of Shabbat, as it differs substantially from normal grinding, it would, according to this view, be forbidden by force of Rabbinic enactment.) The Hida (Rabbi Haim Yosef David Azulai, 1724-1806) applies in this context the famous principle of "Setam Va'yesh Halacha Ke'stam," which means that whenever the Shulhan Aruch codifies a ruling and then cites a dissenting opinion, he sides with the first view recorded. Hence, the Shulhan Aruch allows scraping dirt off a garment on Shabbat.
Would this apply as well to removing dust and the like from a garment by shaking or rubbing the material?
This issue is subject to a debate among the Rishonim (Medieval authorities). Rashi (Rabbi Shlomo Yishaki, famous Biblical and Talmudic commentator, France, 1040-1105) and Rabbenu Hananel (early Talmudic commentator, Egypt, 990-1055) held that removing dust from a garment in this fashion is forbidden on Shabbat. The Shulhan Aruch, however, follows the view of other Rishonim who allow the removal of dirt from a garment on Shabbat by shaking or lightly rubbing the material, and this is indeed the accepted Halachic opinion.
Summary: Halacha forbids cleaning garments with water on Shabbat, but allows removing dirt from a garment by scraping it with one's fingernail, or by shaking or lightly rubbing the material.
