Bittul to Klal Yisrael

אא"ז מו"ר ז"ל הגיד פי' המדרש הנ"ל ע"פ המשנה אם אין אני לי כו'.

My grandfather, my teacher and master, of blessed memory, explained the aforementioned Midrash in light of the Mishnah: "If I am not for myself, who will be for me…" (Avos 1:14).

The Sefas Emes opens by citing his grandfather's teaching, which reads the Midrash through Hillel's famous statement about a person's responsibility for his own avodah.

כי כל אדם נברא על דבר מיוחד מה שא"א לאדם אחר לתקן רק הוא.

For every person was created for a unique task, something that no other person can rectify — only he.

Each soul has its own specific tikkun (rectification) in the world that no one else can accomplish in its place; this is the meaning of "if I am not for myself."

וכן כל שעה ושעה.

And so too every single hour.

Not only is each person's mission unique, but every moment carries its own particular avodah that can be fulfilled only then.

ואעפ"כ כשאני לעצמי מה אני.

And nevertheless, "when I am for myself, what am I?"

Despite each person's irreplaceable role, were he to remain focused only on himself he would amount to nothing — the second half of Hillel's words.

שהעיקר לבטל עבודתו לכלל ישראל.

For the main thing is to nullify one's avodah to the entirety of Klal Yisrael.

The purpose of one's unique service is bittul (self-nullification) — to fold one's personal work into the collective avodah of all Bnei Yisrael.

וז"ש והיו רגלי מביאות לבתי כנסיות כו' עכ"ד.

And this is the meaning of "and my feet would carry me to the synagogues…" — thus far his words.

The image of feet carrying a person to the shul expresses how the individual brings himself into the communal gathering of Klal Yisrael; here his grandfather's teaching concludes.

והשייכות לפ' אם בחקותי כנ"ל שמי שאינו חפץ לגרמייהו רק להיות בטל להשי"ת בוודאי הוא רק ע"י ביטול לכלל ישראל:

And the connection to the parsha "Im bechukosai" is as above: that one who desires nothing for his own sake but only to be nullified to Hashem, surely attains this only through bittul to Klal Yisrael.

The Sefas Emes ties this back to "Im bechukosai" — toiling in Torah for its own sake. True self-nullification before Hashem is reached specifically by surrendering oneself to the collective of Bnei Yisrael, not by standing apart as an individual.

Summary: Every Jew has a unique mission in every moment ("if I am not for myself"), yet self-focus alone is worthless ("when I am for myself, what am I?"). True bittul to Hashem is achieved only by nullifying one's personal avodah into the collective service of Klal Yisrael.