John Chrysostom

"According as it is written, God hath given them the spirit of slumber." Now whence came this blinding? He had indeed mentioned the causes of it before, and turned it all upon their own heads, to show that it was from their unseasonable obstinacy that they had to bear this. And now he speaks of it too. For when he says, "Eyes that they should not see, and ears that they should not hear," he is but finding fault with their contentious spirit. …

Homily on Romans 19 ↗

Theophylact of Ohrid

He brings forth Isaiah as a witness of their blindness, so that he would not appear to be speaking on his own. The words "God gave" are said in place of "granted," that is, He allowed, He permitted them to have "a spirit of slumber." By insensibility he means such a habit of the soul toward evil that is incorrigible and unchangeable; for to be pricked (κατανύσσεσθαι) means to be attached or to cling to something. Having eyes to see the miracles and ears to hear the Lord's teaching, they made use of neither as they ought. …

Commentary on Romans ↗

Thomas Aquinas

Then when he says, as it is written, he clarifies the first part of the conclusion: first, on the authority of Isaiah; second, of David, at and David says. In regard to the first it should be noted that the Apostle bases himself on two passages from Isaiah. For it says in Isaiah: the Lord has poured out upon you a spirit of deep sleep (Isa 29:10). In regard to this he says: God has given them the spirit of compunction, which has to do with a perversity of emotion. For compunction implies a puncturing of the heart or sorrow. …

Commentary on Romans ↗