אור החיים — ויאמר ה'... בהר ההר על גבול ארץ אדום

Q — When God informs Moshe and Aharon of Aharon's impending death, why add the seemingly superfluous geographic note 'on the border of the land of Edom'?

A — Or HaChaim reads it not as locating Hor HaHar but as a critique of Israel's contact with Edom. He parses 'על' as 'because of' and 'גבול' as proximity (not geographic but moral): because they had drawn near to the 'border of wickedness,' Aharon was taken. Citing the midrash 'when you join with the wicked... they lost one tzaddik,' he explains that associating with Edom hastened the righteous one's death — not as the original cause of the decree (which already existed), but in that 'perhaps he could have lived longer days' had they not drawn close to wickedness. This also clarifies 'לאמר': God commands Moshe to tell Israel this very lesson.