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 that in it he had rested from all his work which God created and made.
God rested from His creative acts on the seventh day. This was not rest that followed weariness but the rest that comes from satisfaction and completion of a job well done.