Thematic Bible: Mode of celebrating

[They fought] on the thirteenth day of the month of Adar and rested on the fourteenth, and it became a day of feasting and rejoicing. But the Jews in Susa had assembled on the thirteenth and the fourteenth days of the month. They rested on the fifteenth day of the month, and it became a day of feasting and rejoicing. This explains why the rural Jews who live in villages observe the fourteenth day of the month of Adar as [a time of] rejoicing and feasting. It is a holiday when they send gifts to one another.

because during those days the Jews got rid of their enemies. That was the month when their sorrow was turned into rejoicing and their mourning into a holiday. They were to be days of feasting, rejoicing, and of sending gifts to one another and the poor. Verse ConceptsOvercoming EnemiesPeople Providing FoodRejoicing In God's Works