Eretz Yisrael As Gift
במדרש שמע ישראל כו' הה"ד באזנינו שמענו כו'
In the Midrash on "Shema Yisrael" (Hear, O Yisrael), this is the meaning of the verse, "With our ears we have heard" (Tehillim 44:2).
The Sfas Emes opens by citing the Midrash on "Shema Yisrael," which links it to the verse in Tehillim, "With our ears we have heard," and refers the reader to the Midrash itself.
ע"ש במדרש
See there in the Midrash.
He directs us to study the passage inside the Midrash.
יובן ע"פ ששמעתי ממו"ר א"ז ז"ל שאמר בפסוק לא בצדקתך כו' שמרע"ה אמר כן להודיע כי לא זכו אל א"י בכח צדקתם רק מתנה בזכות אבותינו
This can be understood according to what I heard from my master, my teacher, my grandfather of blessed memory, who said regarding the verse "Not because of your righteousness" (Devarim 9:5) that Moshe Rabbeinu, peace be upon him, said this in order to make known that Bnei Yisrael did not merit Eretz Yisrael through the power of their own righteousness, but rather as a gift, in the merit of our forefathers.
He brings a teaching from his grandfather, the Chiddushei HaRim, that Moshe Rabbeinu stressed "not because of your righteousness" to teach that Bnei Yisrael received Eretz Yisrael not by their own merit but as a gift earned through the zechus of the Avos.
כדי שיהי' שייכות א"י לכל דורות השפלים ג"כ ע"ש
This was so that Eretz Yisrael should have a connection to all the lowly generations as well; see there.
The reason it had to come as a gift through the Avos was so that even the lowly later generations would still have a rightful connection to Eretz Yisrael.
והן הן דברי המד' שמשה רבינו ע"ה הכניס ידיעה זו בלבות בנ"י לידע כי א"י היא במתנה וע"ז הוסד כל המזמור הנ"ל באזנינו שמענו פועל פעלת כו' גוים הורשת ותטעם כו' לא בחרבם ירשו כו' כי ימינך כו'
And these very words are the intent of the Midrash, that Moshe Rabbeinu, peace be upon him, implanted this awareness in the hearts of Bnei Yisrael, to know that Eretz Yisrael is given as a gift; and upon this foundation the entire aforementioned mizmor was composed: "With our ears we have heard, You performed a deed... You drove out nations and planted them... For not by their sword did they inherit the Land... but rather it was Your right hand" (Tehillim 44:2-4).
This is precisely the point of the Midrash: Moshe Rabbeinu planted in the hearts of Bnei Yisrael the awareness that the Land is a gift, and the whole mizmor in Tehillim is built on this idea, stressing that they did not conquer with their own sword but with Hashem's right hand.
לכן צוה ישועות יעקב גם עתה כו' כי לא בקשתי אבטח כו' ע"ש כל המזמור:
Therefore Hashem commanded the salvations of Yaakov even now, for "I do not place my trust in my bow" (Tehillim 44:7); see the entire mizmor there.
Because of this awareness, Hashem grants the salvations of Yaakov in every generation, since Bnei Yisrael place their trust in Him rather than in their own strength.
Summary: The Sfas Emes builds on a teaching from his grandfather, the Chiddushei HaRim, on the verse "Not because of your righteousness." Moshe Rabbeinu emphasized that Bnei Yisrael did not earn Eretz Yisrael through their own merit, but received it as a gift in the zechus of the Avos. The reason it came specifically as such a gift was so that even the lowly later generations would retain a true connection to the Land, which could never be claimed on the strength of their own righteousness. This is the very point that the mizmor "With our ears we have heard" drives home, declaring that Bnei Yisrael did not conquer with their own sword but with the right hand of Hashem. And because they ground their trust in Him rather than in their own power, Hashem continues to command the salvations of Yaakov in every generation.