Exodus 31:12-14

Then the LORD said to Moses, “Say to the Israelites, ‘You must observe my Sabbaths. This will be a sign between me and you for the generations to come, so you may know that I am the LORD, who makes you holy. “ ‘Observe the Sabbath, because it is holy to you. Anyone who desecrates it is to be put to death; those who do any work on that day must be cut off from their people.