Deuteronomy 29:24-26

Even all nations shall say, Wherefore hath the LORD done thus unto this land? what meaneth the heat of this great anger?

Then men shall say, Because they have forsaken the covenant of the LORD God of their fathers, which he made with them when he brought them forth out of the land of Egypt:

For they went and served other gods, and worshipped them, gods whom they knew not, and whom he had not given unto them: