Exodus 31:12-16

Now the Lord spoke to Moses, saying,

“Now as for you, speak to the sons of Israel, saying, ‘You must keep My Sabbaths; for this is a sign between Me and you throughout your generations, so that you may know that I am the Lord who sanctifies you.

Therefore you are to keep the Sabbath, for it is holy to you. Everyone who profanes it must be put to death; for whoever does any work on it, that person shall be cut off from among his people.

For six days work may be done, but on the seventh day there is a Sabbath of complete rest, holy to the Lord; whoever does any work on the Sabbath day must be put to death.

So the sons of Israel shall keep the Sabbath, to celebrate the Sabbath throughout their generations as a permanent covenant.’