'Observing' in the Bible

And it came to pass when the priests were come out of the holy place (for all the priests that were present were hallowed without observing the courses;

On the day after the festival ended, they convened a solemn assembly, because they had been dedicating the altar for seven days and observing the festival for seven days.

They offer burnt sacrifices to the Lord every morning and every evening, along with fragrant incense. They arrange the Bread of the Presence on a ritually clean table and light the lamps on the gold lampstand every evening. Certainly we are observing the Lord our God's regulations, but you have rejected him.

So all the service of the Lord was established that day for observing the Passover and for offering burnt offerings on the altar of the Lord, according to the command of King Josiah.