"all the nations": I might think, literally; it is, therefore, written "these" (i.e., the seven nations). This tells me only of the nations. Whence do I derive (the same for) their abettors? From "all the nations." "from before you": You will progressively increase and they will progressively diminish.
And thus is it written (Shemoth 23:30) "Little by little I will drive them out from before you," and (Ibid. 21) "I will not drive them out from before you in one year." These are the words of R. Yitzchak. R. Elazar b. Azaryah said: If Israel are righteous, why are they afraid of wild animals? Is it not written (Job 5:23) "For with the stones of the field will be your covenant, and the animals of the field will make peace with you"?
And if you ask, why did Joshua undergo all of those exertions (to conquer the nations)? (The answer:) When Israel sinned, they came under the decree of "Little by little I will drive them out from before you." (For it was known to Him that they would sin.)