Esther 9:27
Esther 9:2727the 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.
Witnesses do not observe Purim, and the Watchtower position is that Christians are not bound by festivals established under the old arrangement. The broader teaching is that celebrations not commanded in Scripture — birthdays, Christmas, and the rest — have no place in true worship.
Purim is a useful and non-confrontational example, because nobody is arguing about it. It is not in the Law of Moses. No prophet commanded it. The Jews established it themselves, by common agreement, to commemorate a deliverance God had brought about — and the account of them doing so stands in Scripture without any note of disapproval. So the principle "no commemoration unless commanded" does not hold even within the Old Testament. God's people marked an act of God on their own initiative, and the Bible records it as a good thing. The stronger case is in the New Testament. has Jesus attending the Feast of Dedication — Hanukkah — which commemorates the rededication of the temple in the second century BC, after the Old Testament canon had closed. It is an extra-biblical festival, and he was there. If Jesus could honour a commemoration of a redemptive act of God that no Scripture commanded, the rule against extra-biblical commemorations is not his rule. Compare , , .