'Observe' in the Bible

Then Haman said to King Ahasuerus, “There is a certain people scattered and dispersed among the peoples in all the provinces of your kingdom; their laws are different from those of all other people and they do not observe the king’s laws, so it is not in the king’s interest to let them remain.

This explains why the rural Jews who live in villages observe the fourteenth day of the month of Adar as a time of rejoicing and feasting. It is a holiday when they send gifts to one another.

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

the Jewish people established this celebration, making it a tradition for themselves, for their descendants, and for all who joined with them that they should not fail to observe these two days each year, based on the written instructions, and at the prescribed time.

These days were to be remembered and to be celebrated in every generation and in every family, every province, and every city. The Jews were not to fail to observe these days of Purim; the remembrance of them was not to cease among their descendants.