The Hebrew word translated as rest
actually means to cease or stop.
It does not refer to recovering from exhaustion after a long week of work, but shows that God stopped his work of creation.1 The end of God’s work is thus related to completion and not to fatigue. There was no more creating from nothing left to do; the created order was whole now, requiring only the sustaining grace of God.2
2 And on the seventh day God finished his work that he had done, and he rested on the seventh day from all his work that he had done.