Unity of Yisrael draws down kedushah

בפסוק ונקדשתי בתוך בנ"י וחז"ל למדו מזה דקדושה בתוך עשרה מישראל ע"ש.

On the verse, "And I shall be sanctified amid Bnei Yisrael (venikdashti besoch Bnei Yisrael)" (Vayikra 22:32) — and Chazal derived from this that a davar shebikdushah requires ten of Yisrael; see there.

From "amid Bnei Yisrael," Chazal learn that sanctifying Hashem's Name publicly requires a quorum of ten Jews.

וביאר מו"ז ז"ל כיון דנלמד מתוך בנ"י היינו כשעשרה מישראל מתיחדין בלב אחד להמשיך עליהם הקדושה כו'.

And my grandfather, of blessed memory, explained: since it is learned from "amid Bnei Yisrael," this means when ten of Yisrael unite with one heart (lev echad) to draw kedushah upon themselves, etc.

The Chiddushei HaRim explains that the kedushah of ten comes specifically when those ten join together in a single shared heart to draw holiness down.

ונראה דזה סמיכות פרשת מועדות למצות ונקדשתי.

And it appears that this is the connection (semichus) of the parshah of the moadim (festivals) to the mitzvah of "venikdashti."

This explains why the section of the festivals is placed right after the command "And I shall be sanctified."

דהנה מקראי קודש הם בכח התאחדות בנ"י.

For behold, the "mikra'ei kodesh" (holy convocations) come about through the power of the unification (hisachdus) of Bnei Yisrael.

The festivals are called "holy gatherings" because their sanctity is generated by Bnei Yisrael uniting together.

וכמו כן שבת איתא דהוא רזא דאחד.

And likewise regarding Shabbos, it is brought that it is "the secret of one" (raza de'echad).

Shabbos too is bound up with oneness — it embodies the mystery of unity.

אך השבת היא מתנה לבנ"י דקדושת שבת מביא האחדות בלבות בנ"י.

But Shabbos is a gift (matanah) to Bnei Yisrael, for the kedushah of Shabbos brings the unity into the hearts of Bnei Yisrael.

With Shabbos the order is reversed: its holiness is a gift from above that itself plants achdus in Jewish hearts.

כיון דקדושה ויחוד תלוין זה בזה.

Since kedushah and unity (yichud) are dependent upon one another.

Holiness and unity are intertwined — each draws forth the other.

ובמועדות בא הקדושה בכח התאחדות בנ"י כדאיתא כל ישראל חברים ברגל.

And on the festivals (moados), the kedushah comes through the power of the unification of Bnei Yisrael, as it is brought, "All of Yisrael are chaverim (companions) on the festival" (Chagigah 26a).

Unlike Shabbos, the festivals' holiness flows from the unity of the people, who become as one fellowship when they gather for the regel.

ובכח התאספות ואחדות בנ"י נמשך הקדושה לעולם.

And through the power of the gathering and unity of Bnei Yisrael, the kedushah is drawn into the world.

When Bnei Yisrael assemble in unity, they draw holiness down into the world.

ומצאתי בזוה"ק צ"ג ב' מפורש כדברינו הנ"ל:

And I found in the Zohar HaKadosh, 93b, [it is stated] explicitly in accordance with our words above.

The Sefas Emes notes that the Zohar states this idea explicitly, confirming his explanation.

Summary: "I shall be sanctified amid Bnei Yisrael" teaches that kedushah is drawn down when Jews unite with one heart. This is why the festivals follow that command: the holiness of the moadim is generated by the gathering and unity of Bnei Yisrael — whereas Shabbos, by contrast, is a gift whose holiness itself instills unity in Jewish hearts, since holiness and unity are inseparable.