Deuteronomy 7:22 in the King James Version
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.
Context
21 You shall not be scared of them; for the LORD your God is among you, a great and awesome God.
22 The LORD your God will cast out those nations before you little by little. You may not consume them at once, lest the animals of the field increase on you.
23 But the LORD your God will deliver them up before you, and will confuse them with a great confusion, until they are destroyed.