St Augustine versus Bible

Professor Knuuttila notes in the study described in the previous blog that according to Saint Augustine creation "...took place through God's omnipotence without toil, effort, or industry.

How does Mister Augustine know this?

I see no other source for such a statement as the Philosophers love for accurate definitions in the purest linguistic world of ideas in Neo-Platonism and its emanations?

For the good old practical Bible tells us that the creating of everything actually was quite a job for God. We know this since after completing the work He took a well-deserved rest!

Thus the heavens and the earth were finished, and all the host of them. And on the seventh day God ended His work which He had made; and He rested on the seventh day from all His work which He had made. And God blessed the seventh day and sanctified it, because in it He had rested from all His work which God created and made.
Gen 2:1-3 

Sabbath observance
Sabbath observance is of cosmic importance in Judaism and a hall-mark of the religion.

Trying to emulate the total rest God has commanded on Sabbath day is a major challenge in Judaism and the source of constant worry. Really resting on Sabbath from everything that can be considered work is actually so difficult that some Jewish scholars have suggested "if Sabbath is kept properly even once Messiah will come!"

Since the divine rest on the Seventh Day is of such fundamental importance to the religion of the people of God Saint Augustine and the rest of us should not dismiss it so lightly ultimately relying on our brains and not on what is written in the Holy Scriptures.

If I am wrong about St Augustine in this, please fix my error!