Moses speaks to the Israelites, drawing upon their fresh, lived trauma of the Baal Peor plague to prove the reality of Divine providence and the severe cost of abandoning God. He begins his warnings with the sin of idolatry because it represents the root of all the Commandments [רמב״ן]. Additionally, this specific warning carries immediate weight, as the Israelites were camped directly across from the site of Beth Peor at that very moment [הטור הארוך, חזקוני].
The primary approach among commentators is that the disaster occurred specifically because of the idol Baal Peor. However, another perspective suggests that the name simply identifies the geographic location where the tragedy unfolded [רש״ר הירש].
The plague that struck the camp was not a natural outbreak. A natural disease spreads blindly, harming people without distinction. In this case, however, the destruction was perfectly precise, targeting every single offender without exception [ברכת אשר על התורה]. Only the guilty were wiped out, while everyone who remained loyal to God survived completely unharmed. This supernatural accuracy stands as a clear miracle, proving that the event was not a random disaster but a direct act of Divine providence, which in turn testifies to the divine origin of the Torah itself [רלב״ג, מלבי״ם, ביאור יש״ר].
Commentators explore exactly how the Israelites deteriorated into this tragedy, offering several perspectives. One approach explains that the people never initially intended to worship an idol. Their only goal was to engage in immoral relations with the women of Moab. They relied on their own intellect, assuming they would know exactly when to stop before crossing the line into idolatry. Ultimately, they were dragged into the worship anyway, exposing the profound danger of breaching the boundaries set by the Torah [ספורנו]. A stricter viewpoint emphasizes the absolute severity of idolatry, noting that the offense is so grave that even those who merely walked in the direction of the idol, inclined their minds toward it, or simply entertained the thought of worshipping it were destroyed, even if they had not yet performed any physical act of worship [אור החיים, רש״ר הירש].
A deeper layer connects this tragic event to the prohibition against adding to the Commandments. Surprisingly, many of those who died at Baal Peor had no intention of sinning. On the contrary, they firmly believed they were performing a righteous act. Seeking to mock the idol and expose its disgrace, they thought they were going above and beyond God's instructions. Tragically, in a bitter irony, this exact act of degradation was the official, prescribed method of worshipping Baal Peor. This reveals a harsh but vital lesson: a person must never add to God's Commandments based on personal logic. Altering God's laws through human intervention, even with the best of intentions, is equal to outright rebellion and idolatry, as it places human reasoning on the same level as the will of the Creator [העמק דבר, הכתב והקבלה, מלבי״ם, אדרת אליהו, רש״ר הירש].