Matthew Poole and continuators on Deuteronomy 32:21

21 They have moved me to jealousie with that which is not god, they have provoked me to anger with their vanities: and I will move them to jealousie with those which are not a people , I will provoke them to anger with a foolish nation .

(i. e.) With the Gentile or Heathenish nations, who are none of my people, who scarce deserve the name of a people, as being without yoke, without the knowledge and fear of God which is the foundation of all true policy and government, and without righteous and necessary laws; and many of them are destitute of all government and laws and order, barbarous and rude and savage and brutish in their manners. And yet these people I will prefer before you and take into your stead, receive them and reject you; which, when it came to pass how desperately it provoked the Iews to jealousie, may be gathered from Mat. 21. 43, &c. Act. 11. 2, 3. and 22. 21, 22, 23. 1 Thes. 2. 15, 16.

So the Gentiles were both in the opinion of the Iews, and in truth and reality, notwithstanding all their pretences to wisdom, Rom. 1. 22. there being nothing more foolish or brutish than the worship of Idols. See Ier. 10. 8. 1 Cor. 12. 2.

Marginal references: Hos. 1. 9. Rom. 10. 19.