The Lord's Day is a mystery of the knowledge of the truth that is
not received by flesh and blood, and it transcends speculations.
In this age there is no eighth day, nor is there a true Sabbath.
For he who said that `God rested on the seventh day,' signified
the rest [of our nature] from the course of this life, since the
grave is also of a bodily nature and belongs to this world. Six
days are accomplished in the husbandry of life by means of keeping
the commandments; the seventh is spent entirely in the grave; and
the eighth is the departure from it.
St. Isaac of Syria, The Ascetical Homilies.I