The prophet Yeshayahu (58:13) declares with regard to the observance of Shabbat, "Ve’chibadeto" – "You shall honor it." The Gemara establishes in Masechet Shabbat that among the ways one must show honor to Shabbat is by wearing special clothes on this day: "your clothing on Shabbat shall not be the same as your clothing during the week." Accordingly, the Shulhan Aruch (Orah Haim 262:2) writes, "One must endeavor to have nice clothes for Shabbat" (listen to audio recording for precise citation). The masters of Kabbalah have taught that the garments one wears on Shabbat will also be worn by his soul in the next world. It is therefore critically important to properly observe this Halacha and ensure to wear special, fine clothing on Shabbat.
The Mishna Berura (Rav Yisrael Meir Kagan, 1839-1933) and Kaf Ha’haim (Rav Yaakob Haim Sofer, 1870-1939) clarify that the concept underlying this requirement is the honor of Shabbat, and not the honor of the individual. Therefore, this Halacha applies even if a person is, for whatever reason, alone or among only gentiles on Shabbat. Regardless of whether or not one spends Shabbat among other Jews, he must wear special garments in honor of the occasion of Shabbat.
The Mishna Berura adds that ideally, one should wear on Shabbat clothing that he does not wear at all on weekdays. It might be difficult for a person to ensure not to wear his Shabbat clothes at any time during the week, but this would certainly be a laudable practice to follow if one is capable of doing so.
Hacham Ben Sion Abba Shaul (Israel, 1923-1998), in the introduction to his work Or Le’sion, mentions that the Arizal (Rabbi Yishak Luria, 1534-1572) made a point of wearing on Shabbat at least four white garments, corresponding to the four letters of the Divine Name of "Havaya." This, too, is an admirable practice to follow. One can easily observe this custom by ensuring to wear white undergarments under his pants and shirt, a white shirt and white Sisit. A white Kippa would also qualify as one of the four white garments.
The Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), in his work Rab Pe’alim, addresses the question of whether one must have a special pair of shoes designated for wearing on Shabbat. He proves from a number of sources that one is not required to have a special pair of shoes for Shabbat, though certainly one should polish his shoes and make sure they look presentable for Shabbat. The Kaf Ha’haim writes that one who can afford to purchase a special pair of shoes for Shabbat should preferably do so, though this is not required according to the strict Halacha.
The Mishna Berura writes that one should wear his special Shabbat clothes until Habdala on Mosa’eh Shabbat. The Kaf Ha’haim, however, maintains that one should continue wearing his Shabbat clothes even after Habdala, until he completes his Melave Malka meal.
Both the Mishna Berura and Kaf Ha’haim emphasize that women should ensure to wear their Shabbat clothes before lighting the Shabbat candles on Friday afternoon, as one gives honor to Shabbat by putting on the special clothes before the onset of Shabbat. This might pose some difficulty during the winter months, when Shabbat begins early on Friday afternoon, so women must make a special effort to get dressed in time to light candles while wearing their Shabbat clothes.
In the summer, many people become more lax regarding their mode of dress generally, and, specifically, their mode of dress on Shabbat. As we have seen, Halacha affords great importance to wearing special clothing on Shabbat, and one must ensure to be dressed appropriately throughout Shabbat regardless of the season or the weather.
Summary: Halacha requires wearing special, fine clothing on Shabbat, until at least Habdala, or, according to some, until after his Melave Malka. Women should be wearing their special clothes already when they light the Shabbat candles. Ideally, one should wear on Shabbat clothing that he does not wear at all during the week, and he should preferably wear at least four white garments. (These can include undergarments, Sisit and a Kipa.) Strictly speaking, one does not have to designate special shoes for Shabbat, but one must ensure that they are polished and look presentable.
