Tertullian

For the Jews say, that from the beginning God sanctified the seventh day, by resting on it from all His works which He made; and that thence it was, likewise, that Moses said to the People: "Remember the day of the sabbaths, to sanctify it: every servile work ye shall not do therein, except what pertaineth unto life." Whence we (Christians) understand that we still more ought to observe a sabbath from all "servile work" always, and not only every seventh day, but through all time.