'Of The Month' in the Bible

So the royal scribes were summoned in the first month, on the thirteenth day of the month. Everything Haman commanded was written to the king's satraps and governors who were in every province and to the officials of every people, province by province according to its script and people by people according to its language. In the name of King Ahasuerus it was written and sealed with the king's signet ring.

The Jews who were in Susa then assembled on the fourteenth day of the month of Adar, and they killed three hundred men in Susa. But they did not confiscate their property.

All of this happened on the thirteenth day of the month of Adar. They then rested on the fourteenth day and made it a day for banqueting and happiness.

This is why the Jews who are in the rural country -- those who live in rural cities -- set aside the fourteenth day of the month of Adar as a holiday for happiness, banqueting, holiday, and sending gifts to one another.

to have them observe the fourteenth and the fifteenth day of the month of Adar each year