אסתר, פרק ט׳, פסוק כ״א

The celebration of the Purim holiday was permanently established as a fixed, annual event to mark the victory and survival of the Jewish people [ביאור שטיינזלץ]. However, the observance is not uniform across the entire nation. Instead, the holiday is divided into two distinct dates, reflecting the historical reality of the battles and the precise moments when the existential threat finally passed, allowing for complete peace.

The directive to observe both the fourteenth and fifteenth days of the month does not mean that every individual is required to celebrate for two consecutive days. The primary approach among commentators is that the nation as a whole marks both dates, but the observance is divided by location. Residents of open, unwalled cities celebrate on the fourteenth, while those in Shushan and ancient walled cities celebrate on the fifteenth [עמנואל הרומי, יוסף אבן יחיא].

This difference in dates stems directly from the timeline of the conflict. Haman's original decree called for the destruction of the Jews starting on the thirteenth, but it did not include an end date, leaving the door open for enemies to continue their attacks in the following days. In contrast, the royal permission granted to the Jews for self-defense was strictly limited to the thirteenth alone. In the unwalled cities, after fighting on the thirteenth, the Jews waited to see what would happen the next morning. When no enemies rose against them on the fourteenth, they understood that the danger had entirely passed, and they established that day as their time of joy. In the capital city of Shushan, however, the fighting continued throughout the fourteenth, meaning that safety and celebration were only achieved on the fifteenth [מלבי״ם].

This historical reality explains the date for Shushan, but it raises a question regarding why all cities surrounded by a wall since the days of Joshua share this later celebration date. One perspective suggests that this rule was established to honor the Jews of that specific generation and their actions [אבן עזרא]. A deeper approach connects this practice directly to Jerusalem and the Temple. Because Haman's initial rise to power was tied to his efforts to halt the rebuilding of the Temple, it was fitting that his ultimate downfall be commemorated by showing special honor to Jerusalem. By linking the celebration of the fifteenth to cities walled since the time of Joshua, the holiday serves to remember and elevate the Land of Israel and Jerusalem, which are the true root of the entire event [נחל אשכול].