This acclaimed commentary concludes this section with a fascinating comment: In this light one may understand an oral tradition passed down from the Vilna Gaon (see Chevlei Mashiach Bizemaneinu, p. 134), that when the Russian navy passes through the Bosporus it will be time to put on Sabbath clothes (in anticipation of the coming of Mashiach). What does this passage mean? And what are Sabbath clothes and of what significance are these clothes in general and in light of Messiah’s coming? Shalom
I discussed this issue with Rabbi Dov Eliach, author of the biography "Ha’Gaon" of the Vilna Gaon’s life and teachings. He told me that he is aware that there are writings of Brisker Talmidim in the name of the Brisker Rav regarding this rumor. The Brisker Rav’s opinion was that the Vilna Gaon’s assessment was true for his times and is not relevant nowadays. This is also mentioned in his book " Ha’Gaon " part 2 chapter 24 on Emunah & Bitachon p. 765 note 60. In regard to wearing Shabbat clothes, it is ruled in Halachah than one should wear nice clothes on Shabbat just as one who goes out to greet a king or a Chattan & Kallah, and the way people dress at meetings with important people. It is obvious that people will dress in their finest clothes when greeting the Messiah (see Shabbat 113a and 119a. and Shulchan Aruch Orach Chaim 262).