on one day in all the provinces of King Ahasuerus, on the thirteenth day of the twelfth month, which is the month of Adar.
Esther 8:12
Surrounding context
8:11 By these letters the king permitted the Jews who were in every city to gather together and protect their lives--to destroy, kill, and annihilate all the forces of any people or province that would assault them, both little children and women, and to plunder their possessions,
8:12 on one day in all the provinces of King Ahasuerus, on the thirteenth day of the twelfth month, which is the month of Adar.
8:13 A copy of the document was to be issued as a decree in every province and published for all people, so that the Jews would be ready on that day to avenge themselves on their enemies.