Exodus 31:13

31:13 “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.

Exodus 34:21

34:21 “On six days you may labor, but on the seventh day you must rest; even at the time of plowing and of harvest you are to rest.