Guarding the Covenant Inherits Eretz Yisrael
בענין המנין וברש"י שחתם השי"ת שמו להעיד על יחוסם דכ' ועמך כולם צדיקים כו' יירשו ארץ
Regarding the counting of Bnei Yisrael, Rashi comments that Hashem affixed His Name to attest to their lineage, as it is written, "And your people are all tzaddikim, they shall inherit the land forever" (Yeshayahu 60:21).
Rashi teaches that Hashem placed His Name among Bnei Yisrael in the census to confirm their pure lineage, and the verse promises that such a righteous people will inherit Eretz Yisrael forever.
דכפי שמירת הברית זוכין לנחלת א"י
For it is in accordance with the guarding of the bris (covenant) that one merits the inheritance of Eretz Yisrael.
The Sfas Emes establishes his theme: the merit to inherit Eretz Yisrael is directly proportional to how faithfully Bnei Yisrael guard the bris.
דכ' וכרות עמו הברית כו' לתת לזרעו שלעולם כן הוא לפי שמירת הברית זוכין לא"י
As it is written, "And He made a covenant with him... to give to his seed" (Nechemiah 9:8) — that it is forever thus, that in accordance with the guarding of the bris one merits Eretz Yisrael.
He brings a proof-text showing this is a permanent principle — the covenant Hashem made to give the land to the seed of Avraham is fulfilled according to one's guarding of that bris.
דמנין הראשון הי' ברית הלשון ומנין השני הי' ברית המעור וזהו הברית הוא במעשה ורשימה בגוף שזה צריך כח ביותר לפי שהוא במקום הערלה
The first census embodied the bris of the tongue (guarding one's speech), while the second census embodied the bris of the bris milah; this bris is one of actual deed and an imprint engraved upon the body, which demands greater strength precisely because it is in the place of the orlah (foreskin).
He distinguishes the two censuses: the first corresponds to guarding the tongue and speech, while the second corresponds to the bris milah, which is a physical deed requiring extra strength because it is performed precisely where the orlah was.
וכמו שכל פרט יש לו קומה מן הראש עד הרגלים כן הוא בכלל שמשה רבינו ע"ה תיקן בכלל ישראל ברית הלשון
Just as each individual person has a full stature from the head down to the feet, so too is it with the collective: Moshe Rabbeinu, alav hashalom, rectified within the collective of Bnei Yisrael the bris of the tongue.
Just as a single person has a full body from head to feet, so does the nation as a whole; Moshe Rabbeinu's role was to rectify the "head" level — the bris of the tongue — for the entire collective.
ובסוף הדור היו צריכין לתקן מקום הברית והרגלים
And at the end of that generation they needed to rectify the place of the bris milah and the feet.
By the close of that generation, the remaining work was to rectify the lower levels: the bris milah and the feet.
ואחר תיקון כל הקומה נכנסו לא"י ובנו ביהמ"ק
And after the entire stature was rectified, they entered Eretz Yisrael and built the Beis HaMikdash.
Once the complete spiritual stature of the nation was rectified, top to bottom, they were ready to enter Eretz Yisrael and build the Beis HaMikdash.
וז"ש עומדות היו רגלינו בשעריך ירושלים שזה הי' עדות שתקנו מריש כל דרגין עד בחי' הרגלים
This is the meaning of "Our feet were standing within your gates, Yerushalayim" (Tehillim 122:2) — for this was testimony that they had rectified themselves from the highest of all levels down to the level of the feet.
The verse about feet standing in Yerushalayim testifies that Bnei Yisrael had completed their rectification across the full range of levels, from the very highest down to the feet.
וע"ז הי' העדות בראיות פנים יראה כל זכורך
And concerning this there was testimony through the act of being seen before Hashem, as it is written, "All your males shall appear" (Shemos 23:17).
This completion was confirmed through the mitzvah of appearing before Hashem at the Beis HaMikdash, when every male would present himself.
ובנ"י מתפארים בזה עומדות היו כו' בשעריך ירושלים היא כשהיו נפתחים שערים הפנימיים כדכ' הבנוי' כעיר שחוברה לה שהי' דבוקה בשורש העליון:
And Bnei Yisrael take pride in this — "Our feet were standing... within your gates, Yerushalayim" — referring to when the inner gates were opened, as it is written, "Yerushalayim that is built like a city joined together" (Tehillim 122:3), for she was bound to her supernal root.
Bnei Yisrael glory in having reached Yerushalayim's inner gates — a city "joined together" — meaning the nation became fully unified and bound to its supernal source above.
Summary: The Sfas Emes explains that the merit to inherit Eretz Yisrael flows directly from how Bnei Yisrael guard the bris, as Hashem's covenant with Avraham promised the land to a people who keep it. He reads the two censuses in the midbar as two stages of rectification: the first census corresponds to the bris of the tongue, which Moshe Rabbeinu established for the whole nation, and the second to the bris milah, a physical deed demanding extra strength. Just as an individual has a full stature from head to feet, so too the collective of Bnei Yisrael needed its entire "body" rectified, from the loftiest level down to the feet, by the end of that generation. Only once this complete stature was perfected could they enter Eretz Yisrael and build the Beis HaMikdash. "Our feet were standing in your gates, Yerushalayim" testifies to this total rectification — Yerushalayim a city joined together, with Bnei Yisrael bound to their supernal root.