There is a unique severity in harming another person from a place of darkness and concealment, acting far from any observing eye. Commentators debate whether this hidden harm is physical or verbal. According to one perspective, the harm is literal physical violence. This includes attacking someone under the cover of night or striking a victim who is covered and unable to identify their attacker [ביאור שטיינזלץ]. Another approach views this hidden violence as a reference to murder, one of the most severe transgressions [מלבי״ם]. However, others clarify that the act in question is strictly limited to striking, not murder, because taking a life is explicitly addressed in the immediately following curse [נתינה לגר].
Despite the physical interpretation, the primary approach among commentators is that the hidden harm refers to slander. The necessity for this explanation stems from the emphasis on secrecy. If the prohibition only referred to physical violence, it would imply that striking someone openly is somehow permitted, which is clearly false. Since physical assault is already forbidden elsewhere in the Torah, the focus here must be on verbal attacks [שפתי חכמים]. Some disagree with this reasoning, arguing that physical violence can indeed happen in secret, just as gossip can be spoken openly or quietly. In this view, the Torah deliberately highlights the destructive nature of concealment in both physical and verbal offenses [חזקוני, ברכת אשר].
When understood as slander, the act of striking is fundamentally about lowering and degrading someone. Sharing true derogatory information about a companion strips away their dignity, distinguishing this act from outright false defamation. The victim is specifically defined as a friend, which purposefully excludes individuals who constantly provoke conflict. In fact, condemning habitual quarrelers is permitted and even encouraged for the sake of peace. The element of secrecy also encompasses subtle, disguised speech. This includes situations where a person feigns innocence, drops casual hints, or suggestively remarks that it is better to stay quiet rather than share what truly happened.
On a deeper level, this hidden offense strikes at the very secret of the world, meaning God Himself. When a person degrades another human being, they are actively insulting the Creator's handiwork. It is comparable to someone mocking a crafted vessel, which ultimately insults the artisan who shaped it [הכתב והקבלה].
Looking at the broader structure of the curses pronounced on Mount Gerizim and Mount Ebal, this warning is part of a list of eleven specific curses that correspond to eleven of the Israelite tribes [לבוש האורה, ברטנורא]. The tribe of Simeon is notably absent from this list. This omission occurred either because Jacob refused to bless Simeon before his death, leading to his exclusion from the curses as well [רש״י], or as a consequence of the tribe's severe sin with the daughters of Moab [חזקוני, הדר זקנים]. Within this tribal division, the specific curse against harming a friend in secret is directed at the tribe of Dan. As the eldest of the maidservants' sons—who historically brought negative reports about Leah's children to Joseph in Egypt—the tribe of Dan is given a targeted warning against the destructive power of slander [משכיל לדוד].