The Definition of the Prohibition of Cleaning on Shabbos - Shabbos 147a
The Definition of the Prohibition of Cleaning on Shabbos
The Gemara cites Rav Huna’s ruling that a person who shakes out a garment on Shabbos is liable to bring a chatas (sin-offeing) — i.e., he violates a Torah prohibition. Rashi explains that the case is one in which a person is shaking dust off his garment, and that he is liable to bring a chatas because the shaking-out cleans the garment, thus violating the Torah prohibition of melaben (“whitening”).
R’ Akiva Eiger (Derush V’Chiddush to Shabbos 134b) notes that Rashi evidently contradicts himself. The Gemara there cites Rav Kahana’s ruling that a person who has mud on the outside of his garment is permitted to rub the inside of the garment so that the mud may flake off. Rashi there explains that rubbing on the inside is permitted because it does not resemble cleaning (since the mud is not being rubbed off directly). Rashi adds that in any event the rubbing there is not a Torah violation of melaben, since there is no water involved.
Thus, on the one hand, Rashi to 147a indicates that even when no water is involved a Torah prohibition of melaben may be violated, while on the other hand, Rashi to 134b indicates that a Torah prohibtion is only violated when water is involved.
R’ Akiva Eiger does not offer a resolution to the contradiction. Bigdei Shesh, however, suggests a resolution: The Gemara here, 147a, is discussing a garment soiled by dust, while the Gemara there, 134b, is discussing a garment soiled by mud. It is not necessary to use water to rid a garment of dust, but in order to cleanse a garment of mud, one really needs to use water. Hence, it is readily understood that in regard to dust, shaking out is an adequate manner of cleansing, and thus a Torah violation, while in regard to mud, rubbing without water is not an adequate manner of cleansing, and therefore not a Torah violation.