Parallel
Esther 8:12
Jewish Publication Society 1917 · Berean Standard Bible
upon one day in all the provinces of king Ahasuerus, namely, upon the thirteenth day of the twelfth month, which is the month Adar.
The single day appointed throughout all the provinces of King Xerxes was the thirteenth day of the twelfth month, the month of Adar (note: Adar is the twelfth month of the Hebrew lunar calendar, usually occurring within the months of February and March.).