Cross reference
Deuteronomy 7:22
22 Yahweh your God will cast out those nations before you by little and little: you may not consume them at once, lest the animals of the field increase on you.
Exodus 23:29-30
29 I will not drive them out from before you in one year, lest the land become desolate, and the animals of the field multiply against you.
30 Little by little I will drive them out from before you, until you have increased and inherit the land.
Joshua 15:63
63 As for the Jebusites, the inhabitants of Jerusalem, the children of Judah couldn't drive them out: but the Jebusites dwell with the children of Judah at Jerusalem to this day.