But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work...
Exodus 20:10
"God created
the world and gave existence to man upon it. 
To him He gave life and
breath, and all things.
---Man therefore owes everything to God.
Every
faculty of his mind, every power of his being, all his strength and all
his time belong of right to the Creator.
*It was therefore the benevolence
of the Creator that gave to man six days for his own wants.
*And in setting
apart the seventh day to a holy use in memory of His own rest, the Most
High was reserving unto Himself one of the seven days, when he could
rightly claim all as His.
-*-The six days therefore are the gift of God to
man, to be rightly employed in secular affairs, not the seventh day, the
gift of man to God.
The fourth Commandment, therefore, does not require
man to give something of his own to God, but it does require that man
should not appropriate to himself that which God has reserved for His own
worship.
To observe this day then is to render to God of the things that
are His; to appropriate it to ourselves is simply to rob God."
J.N. Andrews