Exodus 31:12-16

12And the LORD said to Moses, 13“Tell the Israelites, ‘Surely you must keep My Sabbaths, for this will be a sign between Me and you for the generations to come, so that you may know that I am the LORD who sanctifies you. 14Keep the Sabbath, for it is holy to you. Anyone who profanes it must surely be put to death. Whoever does any work on that day must be cut off from among his people. 15For six days work may be done, but the seventh day is a Sabbath of complete rest, holy to the LORD. Whoever does any work on the Sabbath day must surely be put to death.

16The Israelites must keep the Sabbath, celebrating it as a permanent covenant for the generations to come.