Exodus 23:28-30

And I will send the hornet before you, and it will drive out the Hivites, the Canaanites, and the Hittites from before you. I will not drive them out from before you in one year, lest the land become a desolation and the wild animals multiply against you. Little by little I will drive them out from before you until you are fruitful and take possession of the land.