Covenant Binding All Generations
א"נ היום כו' לעברך כו'
It says, "This day... that you should pass into..." (Devarim 29:11).
The Sfas Emes opens with the pasuk describing the day Bnei Yisrael entered the covenant with Hashem.
דאיתא כנסי' שהיא לש"ש סופה להתקיים
For it is taught that any gathering that is for the sake of Heaven will ultimately endure.
He cites the principle that any assembly undertaken purely for Hashem's sake has lasting, eternal endurance.
ומשה רבינו ע"ה כינס את בנ"י בדורו שיהי' כוונתם רק לשמו ית' כמ"ש לעברך בברית
And Moshe Rabbeinu, peace be upon him, gathered together Bnei Yisrael of his generation so that their intent should be solely for the sake of His Name, may He be blessed, as it is written, "that you should pass into the covenant" (Devarim 29:11).
Moshe Rabbeinu gathered his generation precisely so their motive would be entirely l'shem Shamayim, which is why the verse frames it as passing into a covenant.
וע"י שכיוונו לש"ש נשאר זה הברית לכל הדורות כמ"ש את אשר ישנו כו' איננו
And because they directed their intent for the sake of Heaven, this covenant remained binding for all the generations, as it is written, "both with him that stands here... and with him that is not here" (Devarim 29:14).
Because their intent was pure, the covenant was sealed not only for them but for every future generation, as the pasuk includes even those not physically present.
ודורו של מרע"ה הי' כולל כל הדורות שלפניו ולאחריו
And the generation of Moshe Rabbeinu, peace be upon him, encompassed within it all the generations that came before him and all that would come after him.
Moshe's generation served as a container that held within it every generation, past and future.
כדאיתא שכל הנשמות מבריאת עולם עד סוף העולם עמדו בזה הברית
As it is taught, that all the neshamos from the creation of the world until the end of the world stood present at this covenant.
This reflects the teaching that every neshamah that would ever exist stood together at that covenant.
וכל דבר שהי' בכלל כו' ללמד על הכלל כולו כו'
And by the principle that "anything that was included in a general statement... is singled out to teach about the entire general category" (a rule of derashah),
He applies the derashah principle that a detail singled out from a general rule teaches about the whole category.
שבכל דור ודור כפי הכנסי' שמתאספין לש"ש לקבל עול מלכותו ית' מתאספין עמהם כל הדורות
in every single generation, in accordance with the gathering of those who assemble for the sake of Heaven to accept the yoke of His kingship, may He be blessed, all the generations are gathered together along with them.
So in each generation, when people gather l'shem Shamayim to accept the yoke of Heaven, all the generations are spiritually drawn in together with them.
אך לא הי' דור כדורו של מרע"ה שקיבלו התורה
However, there was no generation like the generation of Moshe Rabbeinu, peace be upon him, who received the Torah.
Yet no generation matched Moshe's generation, which actually received the Torah at its source.
ולכן הי' כל מעשיהם הכנה לכל הדורות
And therefore all of their deeds were a preparation for all the generations.
Therefore everything that generation did functioned as the preparation and foundation for every later generation.
ובכל דור מתקיים בפועל קצת ממה שהוכן אז
And in every generation, a small measure of that which was prepared back then is actually fulfilled in practice.
Each subsequent generation realizes in practice only a portion of the potential that was established at Sinai.
וז"ש והי' כי יבאו עליך הדברים האלה כו'
And this is the meaning of "And it shall come to pass, when all these things come upon you..." (Devarim 30:1),
He reads the pasuk about "all these things coming upon you" as pointing to this unfolding.
שלדורות אחרונים יתקיימו אלה הדברים בפועל:
that for the later generations these matters will be fulfilled in actual practice.
The covenant's content is destined to be actualized concretely specifically in the later generations.
Summary: The Sfas Emes teaches that any gathering done for the sake of Heaven endures forever, and that Moshe Rabbeinu assembled Bnei Yisrael into the covenant with this pure intent. Because of that purity, the covenant became binding on all generations, for the generation of Moshe Rabbeinu contained within it every neshamah that would ever live, and they all stood together at that covenant. Drawing on the derashah that a detail singled out teaches about the whole, he explains that whenever a generation gathers l'shem Shamayim to accept the yoke of His kingship, all the generations are drawn in with them. Yet no generation equaled Moshe's, which received the Torah itself, so their deeds were the preparation for all of history. Each later generation actualizes in practice a small measure of that which was prepared at Sinai, and this is what the pasuk means that these matters will ultimately be fulfilled in deed for the later generations.