We observe the 7th day as commanded in Ex.20, and Deut. 5.
Deut. 5:12 ‘Observe the Sabbath day, to keep it holy, as the Lord your God commanded you. 13 Six days you shall labor and do all your work, 14 but the seventh day is the Sabbath of the Lord your God. In it you shall do no work: you, nor your son, nor your daughter, nor your male servant, nor your female servant, nor your ox, nor your donkey, nor any of your cattle, nor your stranger who is within your gates, that your male servant and your female servant may rest as well as you.