ordinance

Definition:

An ordinance is a public regulation or law that gives rules or instructions for people to follow. This term is related to the term "ordain."

Sometimes an ordinance is a custom that has become well established through years of practice.
In the Bible, an ordinance was something that God commanded the Israelites to do. Sometimes he commanded them to do it forever.
The term "ordinance" could be translated as "public decree" or "regulation" or "law," depending on the context.