Exodus 31:12-16

12The Lord said to Moses,

13“Tell the Israelites, ‘Surely you must keep my Sabbaths, for it is a sign between me and you throughout your generations, that you may know that I am the Lord who sanctifies you.

14So you must keep the Sabbath, for it is holy for you. Everyone who defiles it must surely be put to death; indeed, if anyone does any work on it, then that person will be cut off from among his people.

15Six days work may be done, but on the seventh day is a Sabbath of complete rest, holy to the Lord; anyone who does work on the Sabbath day must surely be put to death.

16The Israelites must keep the Sabbath by observing the Sabbath throughout their generations as a perpetual covenant.