Question: May one use bar soap on Shabbat to wash one’s hands and the like or is this forbidden?
Answer: In the previous Halacha, we have discussed the disagreement among the Rishonim regarding crushing ice on Shabbat and turning it into liquid, whereby according to the Sefer Ha’Terumah, this is prohibited as a result of the Torah prohibition to create a new substance on Shabbat while according to the Rambam, Ramban, and Rashba, there is no Torah prohibition here at all; rather, the prohibition to crush ice is a rabbinic enactment because crushing ice and turning it into a liquid is similar to the Torah prohibition of squeezing fruits for their juice. We have also mentioned that Maran Ha’Shulchan Aruch rules in accordance with the opinion of the Rambam, Ramban, and Rashba that the prohibition to crush ice is only rabbinic and is because of its similarity to squeezing fruits. The Rama, on the other hand, rules that one must be concerned with the opinion of the Sefer Ha’Terumah that the source of this prohibition is biblical.
Based on this, Maran Rabbeinu Ovadia Yosef zt”l begins his discussion about using bar soap on Shabbat. It would seem that using soap with water and turning it into a liquid is similar to crushing ice and turning it into liquid which is forbidden on Shabbat. Nevertheless, according to Maran Ha’Shulchan Aruch that the reason why crushing ice is forbidden on Shabbat is because this is similar to squeezing fruits and not because of the prohibition to create a new substance on Shabbat, it would seem that this reason would not apply to “melting” soap, for this melting can only be done along with water and the soap cannot melt naturally on its own as is the case regarding ice or fruit. This distinction is indeed recorded by Hagaon Harav Yitzchak Lampronti in his Sefer Pachad Yitzchak where he writes that according to Maran Ha’Shulchan Aruch, there is no prohibition to use soap on Shabbat. (See Chazon Ovadia-Shabbat, Part 3, page 46 among other places.)
Thus, Sephardic and Middle Eastern Jews who follow the rulings of Maran Ha’Shulchan Aruch may act leniently and wash their hands with bar soap on Shabbat. Ashkenazim, however, who follow the rulings of the Rama should act stringently regarding this matter unless there is a great need to do so, such as a doctor who must wash his hands after examining an ill patient for health reasons (and no liquid soap or hand-sanitizer is available).