'Observance' in the Bible

and he told them, "This is what the LORD said: "Tomorrow is a Sabbath observance, a holy Sabbath to the LORD. Bake what you want to bake and boil what you want to boil, and put aside whatever remains to be kept for yourselves until morning.'"

The Israelis are to keep the Sabbath to make the Sabbath observance a perpetual covenant from generation to generation.