Esther 9:21

Overview - Esther 9
1	The Jews slay their enemies, with the ten sons of Haman.
12	Ahasuerus, at the request of Esther, grants another day of slaughter, and Haman's sons to be hanged.
20	The two days of Purim are made festival.

Esther 9:21  (King James Version)
To stablish this among them, that they should keep the fourteenth day of the month Adar, and the fifteenth day of the same, yearly,