Esther 8:10-12

He wrote [a decree] in the name of King Ahasuerus, and sealed it with the king’s ring, and sent letters by couriers on horseback, riding on the royal [mail] relay horses, the offspring of the racing mares. In it the king granted the Jews who were in every city the right to assemble and to defend their lives; to destroy, to kill, and to annihilate any armed force that might attack them, their little children, and women; and to take the enemies’ goods as plunder, on one day in all the provinces of King Ahasuerus, the thirteenth [day] of the twelfth month (that is, the month of Adar).