“Third, it is unreasonable to suppose any other, than that God’s working six days and resting the seventh, and blessing and hallowing it, was to be of general use in determining this matter. It was written that the practice of mankind in general might some way or other be regulated by it. What could be the meaning of God’s resting the seventh day and hallowing and blessing it, which he did before the giving of the fourth commandment, unless he hallowed and blessed it with respect to mankind? For he did not bless and sanctify it with respect to himself, or that he within himself might observe it: as that is most absurd. And it is unreasonable to suppose that he hallowed it only with respect to the Jews, a particular nation, which rose up above two thousand years after.
So much therefore must be intended by it, that it was his mind, that mankind should, after his example, work six days and then rest and hallow or sanctify the next following: that they should sanctify every seventh day, or that the space between rest and rest, one hallowed time and another, among his creatures here upon earth, should be six days. — So that it hence appears to be the mind and will of God that not only the Jews, but man in all nations and ages, should sanctify one day in seven: which is the thing we are endeavoring to prove.”
~Jonathan Edwards, “The Perpetuity and Change of the Sabbath”
Source and read more: http://www.biblebb.com/files/edwards/sabbath.htm