The emperor said to Rabbi Yehoshua ben Hananyah: Why does a dish cooked for the Sabbath give off such a fragrance? He said to him: We have a certain spice, and Sabbath is its name, which we cast into the dish, and its fragrance spreads. He said to him: Give us some of it. He said to him: For anyone who keeps the Sabbath, it is effective for him, but for one who does not keep the Sabbath, it is not effective for him.
The Spice Of The Sabbath
Shabbat 119a
אָמַר לוֹ קֵיסָר לְרַבִּי יְהוֹשֻׁעַ בֶּן חֲנַנְיָא: מִפְּנֵי מָה תַּבְשִׁיל שֶׁל שַׁבָּת רֵיחוֹ נוֹדֵף? אָמַר לוֹ: תַּבְלִין אֶחָד יֵשׁ לָנוּ וְשַׁבָּת שְׁמוֹ, שֶׁאָנוּ מְטִילִין לְתוֹכוֹ וְרֵיחוֹ נוֹדֵף. אָמַר לוֹ: תֵּן לָנוּ הֵימֶנּוּ. אָמַר לוֹ: כׇּל הַמְשַׁמֵּר אֶת הַשַּׁבָּת — מוֹעִיל לוֹ, וְשֶׁאֵינוֹ מְשַׁמֵּר אֶת הַשַּׁבָּת — אֵינוֹ מוֹעִיל לוֹ.