'Observe' in the Bible

You shall also observe the Feast of Unleavened Bread, because on this very day I brought your hosts [grouped according to tribal armies] out of the land of Egypt; therefore you shall observe this day throughout your generations as an ordinance forever.

You shall observe this event [concerning Passover] as an ordinance for you and for your children forever.

So the Israelites shall observe the Sabbath, to celebrate the Sabbath throughout their generations as a perpetual covenant.’

“Be sure to observe what I am commanding you this day: behold, I am going to drive out the Amorite before you, and the Canaanite, the Hittite, the Perizzite, the Hivite, and the Jebusite.

You shall observe and celebrate the Feast of Weeks (Harvest, First Fruits, or Pentecost), the first fruits of the wheat harvest, and the Feast of Ingathering (Booths or Tabernacles) at the year’s end.