The command “remember the Sabbath day to keep it holy” is therefore exactly equivalent to saying “remember the rest day to keep it holy.”
The explanation which follows sustains this statement: “The seventh day is the Sabbath [or rest day] of the Lord thy God.”
The origin of this rest day is given in these words: “For in six days
the Lord made heaven and earth, the sea and all that in them is, and rested the seventh day: wherefore the Lord blessed the Sabbath day and hallowed it.”
That which is enjoined in the fourth commandment is to keep holy the rest day of the Lord.
And this is defined to be the day on which he rested from the work of creation.
Moreover the fourth commandment calls the seventh day the Sabbath day at the time when God blessed and hallowed that day, therefore the Sabbath is an institution dating from the foundation of the world.
The fourth commandment points back to the creation for the origin of its obligation; and when we go back to that point, we find the substance of the fourth commandment given to Adam: “God blessed the seventh day and sanctified it,” i.e., set it apart to a holy use." J.N. Andrews
