Shabbos refines body and soul

בשירת האזינו השמים (כו') ותשמע הארץ.

In the song of Haazinu: "Give ear, O heavens... and let the earth hear" (Devarim 32:1).

The Sefas Emes opens with the dual address of Moshe's song — calling upon both heaven and earth.

כי האדם כלול מעליונים ותחתונים ובקבלת התורה נתעלו בני ישראל אל בחי' השמים זה חלק הראשון.

For man is composed of upper [elements] and lower [elements], and through the receiving of the Torah Bnei Yisrael were elevated to the aspect of "heavens" — this is the first part.

A person is a blend of higher (spiritual) and lower (physical) components. At Matan Torah, the soul-dimension of Yisrael was raised to the level of "shamayim" (heaven) — that was the first stage of their refinement.

אח"כ ירכיבהו על במתי ארץ היא ההרכבה בד' יסודות זה התיקון הי' בקישוי לפי שלא נכנס משה רע"ה עמנו לארץ ישראל.

Afterward, "He made him ride upon the heights of the earth" (Devarim 32:13) — this is the combination within the four elements; this rectification (tikkun) came with difficulty, because Moshe Rabbeinu did not enter Eretz Yisrael together with us.

The second stage is to elevate even the earthly, bodily side — "the heights of the earth," the body built of the four elements. This tikkun of the physical proved hard to achieve, and its incompleteness is bound up with the fact that Moshe did not lead us into Eretz Yisrael.

ולכן וישמן ויבעט ולעתיד יהי' מתוקן גם חלק הגוף.

And therefore "[Yeshurun] grew fat and kicked" (Devarim 32:15); but in the future the portion of the body too will be rectified.

Because the body was not yet fully refined, it could rebel — "grew fat and kicked." Ultimately, in the future, even the bodily portion of man will be fully repaired.

ומרע"ה נק' איש האלקים מחצה איש מחצה אלקים שהי' מתוקן כראוי.

And Moshe Rabbeinu is called "Ish HaElokim" (a man of God) — half man, half divine — for he was rectified as is fitting.

Moshe is the model of the perfectly balanced person: "half man, half God," meaning both his physical and spiritual sides were properly refined and integrated.

והנה בשבת קודש מאיר בחי' מרע"ה והיא מעין עוה"ב וכ' בי' והרכבתיך על במתי ארץ שבו גם חלק הגוף מתוקן.

Now on Shabbos Kodesh the aspect of Moshe Rabbeinu shines, and it is a foretaste of the World to Come (me'ein olam haba), and it is written of it, "I will make you ride upon the heights of the earth" (Yeshayahu 58:14) — for on it the bodily portion too is rectified.

Shabbos radiates the perfected, integrated quality of Moshe and is a taste of the future world. On Shabbos even the physical body is elevated, fulfilling "I will make you ride upon the heights of the earth."

ולכן מצוה לענג הגוף ג"כ בשבת והוא נחלה בלי מצרים תיקון הגמור.

Therefore it is a mitzvah to give pleasure to the body as well on Shabbos, and it is "an inheritance without boundaries" (nachalah beli metzarim) — the complete rectification.

Precisely because Shabbos refines the body, oneg Shabbos (delighting the body) is itself a mitzvah. Shabbos is the "boundless inheritance," the total tikkun in which body and soul are both uplifted.

וזהו עדות השבת שהוא זכר למעשה בראשית כמו שהי' קודם החטא וכמו שיהי' לעתיד:

And this is the testimony of Shabbos, that it is a remembrance of the work of creation — as it was before the sin and as it will be in the future.

Shabbos bears witness to maaseh bereishis, restoring the world to its pristine state before Adam's sin and previewing its perfected state in the future — when body and soul will be wholly rectified.

Summary: Man is composed of an upper (soul) and lower (body) dimension. At Matan Torah the soul was raised to "heaven," but the harder tikkun — elevating the earthly body — remained incomplete because Moshe did not enter Eretz Yisrael, leaving room for "grew fat and kicked." Moshe, "Ish HaElokim," was the perfectly integrated man. Shabbos radiates his quality as a foretaste of olam haba, refining even the body — hence oneg Shabbos is a mitzvah — restoring creation to its pre-sin state and previewing the complete future tikkun.