Returning a Fellow Spiritually
לא תראה כו' שור אחיך כו' השב תשיבם כו'
"You shall not see your brother's ox... and ignore them; you shall surely return them" (Devarim 22:1).
The Torah's command not to ignore a brother's lost ox but to return it is read as a charge concerning anyone who sees his fellow straying from the right path.
י"ל שכל מי שרואה בחבירו תועה מדרך הישר
It may be said that this refers to anyone who sees his fellow straying from the upright path,
The Sfas Emes opens a deeper reading: the obligation applies to one who notices another Yid going off the straight derech.
וי"ל שור לשון הבטה
And it may be said that "shor" (ox) is an expression denoting gazing and looking,
He hints that the word "shor" can be linked to gazing, since one corrects through how he looks at his fellow.
או שאר תנועה רעה צריך לתקנו
Or some other improper movement, and he must rectify it.
Whether it is an errant glance or some other improper movement that a person observes, he is duty-bound to set it right.
והעצה ע"י תשובה כמ"ש בסה"ק כל מה שרואה האדם שייך לו וצריך לשוב ע"ז ועי"ז מביא הרהור תשובה גם בחבירו וז"ש השב תשיבם
And the counsel for this is through teshuvah, as it is written in the holy seforim that whatever a person sees pertains to himself and he must do teshuvah upon it, and through this he brings a stirring of teshuvah in his fellow as well; this is the meaning of "you shall surely return them" (hashev teshivem).
The way to fix it is through teshuvah: the holy seforim teach that whatever a person sees is connected to himself and demands his own teshuvah, and that very teshuvah awakens a parallel stirring of teshuvah in the other person.
כי כלל ישראל הם א' וכשא' מקלקל צד קדושה שבו נשאר בכלל ישראל כמ"ש ז"ל זכה נוטל חלק חבירו כו'
For Klal Yisrael are one, and when one person damages the aspect of kedushah within himself, it yet remains within Klal Yisrael, as Chazal said: one who merits takes the portion of his fellow.
Since all of Bnei Yisrael form a single unit, when one Yid harms the kedushah within him, that kedushah is not lost from the collective but endures within Klal Yisrael, just as Chazal taught that the one who is zocheh receives his fellow's share.
אבל האדם צריך לחזור האבידה לבעליו
But a person must return the lost object to its owner.
Nonetheless, the individual is charged to restore that lost spiritual property to its rightful owner.
אשר תאבד ממנו ומצאתה
"That is lost from him, and you find it" (Devarim 22:3) —
The phrase "that is lost from him, and you find it" points to a fellow Yid's lost kedushah which one is positioned to recover.
לא תוכל להתעלם שצריך להיות שלא יוכל לסבול ולהתעלם מחטא חבירו ג"כ:
"You shall not be able to ignore it" (Devarim 22:3): a person must reach the level where he is unable to bear it or ignore the sin of his fellow either.
"You shall not be able to ignore it" sets the avodah's bar: a person must grow so sensitive that he simply cannot tolerate or look away from his fellow's sin.
Summary: The Sfas Emes reads the mitzvah of hashavas aveidah, returning a brother's lost ox, as a teaching about spiritual responsibility for one another. When a person sees his fellow straying from the upright path, that very sight is no accident: the holy seforim teach that whatever one observes pertains to himself and calls for his own teshuvah, and through doing teshuvah he awakens a stirring of teshuvah in his fellow as well. Because all of Bnei Yisrael are one, the kedushah a person damages is not truly lost to Klal Yisrael but remains within the collective, as Chazal taught that the one who merits takes his fellow's portion. The avodah, then, is to restore the lost spiritual object to its owner, reaching such a level of sensitivity that one can no longer bear or ignore the sin of his fellow.