אורח חיים רמ״בOrach Chayim 242

Se’if 1א׳

אֲפִלּוּ מִי שֶׁצָּרִיךְ לַאֲחֵרִים, אִם יֵשׁ לוֹ מְעַט מִשֶּׁלּוֹ צָרִיךְ לְזָרֵז עַצְמוֹ לְכַבֵּד אֶת הַשַּׁבָּת; וְלֹא אָמְרוּ: עֲשֵׂה שַׁבָּתְךָ חֹל וְלֹא תִּצְטָרֵךְ לַבְּרִיּוֹת, אֶלָּא לְמִי שֶׁהַשָּׁעָה דְּחוּקָה לוֹ בְּיוֹתֵר; עַל כֵּן צָרִיךְ לְצַמְצֵם בִּשְׁאָר יָמִים כְּדֵי לְכַבֵּד הַשַּׁבָּת. מִתַּקָּנַת עֶזְרָא שֶׁיִּהְיוּ מְכַבְּסִים בְּגָדִים בַּחֲמִישִׁי בְּשַׁבָּת, מִפְּנֵי כְּבוֹד הַשַּׁבָּת. הַגָּה: נוֹהֲגִין לָלוּשׁ כְּדֵי שִׁעוּר חַלָּה בַּבַּיִת, לַעֲשׂוֹת מֵהֶם לְחָמִים לִבְצֹעַ עֲלֵיהֶם בְּשַׁבָּת וְיוֹם טוֹב, (סֶמֶךְ מִמָּרְדְּכַי רֵישׁ מַסֶכֶת רֹאשׁ הַשָּׁנָה), וְהוּא מִכְּבוֹד שַׁבָּת וְיוֹם טוֹב, וְאֵין לְשַׁנּוֹת. יֵשׁ שֶׁכָּתְבוּ שֶׁבְּמִקְצָת מְקוֹמוֹת נָהֲגוּ לֶאֱכֹל מֻלְיְתָא, שֶׁקּוֹרִין פשטיד"א, בְּלֵיל שַׁבָּת, זֵכֶר לַמָּן שֶׁהָיָה מְכֻסֶּה לְמַעְלָה וּלְמַטָּה (מַהֲרִי"ל) וְלֹא רָאִיתִי לָחוּשׁ לָזֶה.

Even regarding someone who depends on others for his livelihood, if he has [even just] some [food] of his own, he must make an effort to honor the Shabbat. The halackhic decisors [poskim] who said, "make your Shabbat as a weekday so that you not rely on others," only said it regarding one in a time of dire need. Therefore [a person who has a bit of their own food, i.e., the initial situation discussed,] must practice restraint during the week so that he can honor the Shabbat. This is based on the decree of Ezra, that people should wash clothes on Thursday (i.e., prepare during the week) for the honor of Shabbat. Rema: We customarily knead a quantity of dough that is sufficient to become obligated in the mitzvah of challah, in the home. With these, we bake breads that we will then break on Shabbat and holidays. This is one of the [many ways] in which we honor Shabbat and holidays, and one must not deviate from this custom. Some write that in a few places they are accustomed to eat mulitha, also known as pashtida, on the night of Shabbat as a remembrance to the manna, which was covered above and below. [Maharil; I don’t see that one should be concerned to follow this.]