Deuteronomy 7:21-23

Thou shalt not be affrighted at them: for the LORD thy God is among you, a mighty God and terrible.

And the LORD thy God will put out those nations before thee by little and little: thou mayest not consume them at once, lest the beasts of the field increase upon thee.

But the LORD thy God shall deliver them unto thee, and shall destroy them with a mighty destruction, until they be destroyed.