Deuteronomy 7:21-23

You are not to be frightened of them, because ADONAI your God is there with you, a God great and fearsome.

ADONAI your God will expel those nations ahead of you little by little; you can't put an end to them all at once, or the wild animals will become too numerous for you.

Nevertheless, ADONAI your God will give them over to you, sending one disaster after another upon them until they have been destroyed.