the Jews bound themselves to establish the custom that they and their descendants and all who join them should not fail to celebrate these two days at the appointed time each and every year, according to their regulation.
Jewish Publication Society of America Version (JPS1917) - Esther 9:27 >the Jews ordained, and took upon them, and upon their seed, and upon all such as joined themselves unto them, so as it should not fail, that they would keep these two days according to the writing thereof, and according to the appointed time thereof, every year;