The Talmud teaches that a person receives a neshamah yeteirah (an additional soul) on Shabbat, and at the conclusion of Shabbat it departs. This additional dimension of the soul is uniquely sustained by the Shabbat experience.
אִי הָכִי, לָא לִעַנְשׁוּ גּוֹיִם עֲלַהּ? שַׁבָּת — אוֹדוֹעֵי אוֹדְעִינְהוּ, מַתַּן שְׂכָרָהּ — לָא אוֹדְעִינְהוּ. וְאִי בָּעֵית אֵימָא: מַתַּן שְׂכָרָהּ נָמֵי אוֹדְעִינְהוּ, נְשָׁמָה יְתֵירָה — לָא אוֹדְעִינְהוּ. דְּאָמַר רַבִּי שִׁמְעוֹן בֶּן לָקִישׁ: נְשָׁמָה יְתֵירָה נוֹתֵן הַקָּדוֹשׁ בָּרוּךְ הוּא בָּאָדָם עֶרֶב שַׁבָּת, וּלְמוֹצָאֵי שַׁבָּת נוֹטְלִין אוֹתָהּ הֵימֶנּוּ, שֶׁנֶּאֱמַר: ״שָׁבַת וַיִּנָּפַשׁ״, כֵּיוָן שֶׁשָּׁבַת וַוי אָבְדָה נֶפֶשׁ.
The Gemara challenges: If it is so that it was given in secret so that not everyone knew about it, the gentiles should not be punished for not wanting to accept it; they are liable to receive punishment for refusing to accept the other mitzvot of the Torah. The Gemara answers: The Holy One, Blessed be He, did inform them of the concept of Shabbat, but He did not inform them of the reward for the fulfillment of the mitzva. And if you wish, say instead that He also informed the gentiles of its reward, but about the idea of the additional soul given to each person on Shabbat He did not inform them. As Rabbi Shimon ben Lakish said: The Holy One, Blessed be He, gives a person an additional soul on Shabbat eve, and at the conclusion of Shabbat removes it from him, as it is stated: “He ceased from work and was refreshed [vayinafash]” (Exodus 31:17). Rabbi Shimon ben Lakish expounds the verse as follows: Since he ceased from work, and now Shabbat has concluded and his additional soul is removed from him, woe [vai] for the additional soul [nefesh] that is lost.