The Jews in Susa, however, had assembled on the thirteenth and the fourteenth days of the month. So they rested on the fifteenth day, making it a day of feasting and joy.

Esther 8:11
By these letters the king permitted the Jews in each and every city the right to assemble and defend themselves, to destroy, kill, and annihilate all the forces of any people or province hostile to them, including women and children, and to plunder their possessions.

Esther 9:2
In each of the provinces of King Xerxes, the Jews assembled in their cities to attack those who sought to harm them. No man could withstand them, because the fear of them had fallen upon all peoples.

Esther 9:21
to establish among them an annual celebration on the fourteenth and fifteenth days of the month of Adar

But the Jews that were at Shushan assembled together on the thirteenth day thereof, and on the fourteenth thereof; and on the fifteenth day of the same they rested, and made it a day of feasting and gladness.