10 Let their eyes be darkened, that they may not see, and bow down their back alway.
[AD 253] Origen of Alexandria on Romans 11:10
God will do this because it is better not to know anything at all than to know something badly.

[AD 407] John Chrysostom on Romans 11:9-10
"Let their table be made a snare, and a trap, and a stumbling-block."

That is, let their comforts and all their good things change and perish, and let them be open to attack from any one. And to show that this is in punishment for sins that they suffer this, he adds, "and a recompense unto them."

"Let their eyes be darkened that they may not see, and bow Thou down their back alway."

Do these things then still require any interpreting? Are they not plain even to those ever so senseless? And before our words, the very issue of facts has anticipated us in bearing witness to what was said. For at what time have they ever been so open to attacks? at what time such an easy prey? at what time hath He so "bowed down their backs?" At what time have they been set under such bondage? And what is more, there is not to be any unloosing from these terrors. And this the prophet hath also hinted. For he does not say only, "bow Thou down their back," but, "forever bow Thou down." But if thou art disposed to dispute, O Jew, about the issue, from what hath gone before learn also the present case. Thou didst go down to Egypt; and two hundred years passed, and God freed thee speedily from that bondage, and that though thou wert irreligious, and wentest a whoring with the most baneful whoredom. Thou wast freed from Egypt, and thou didst worship the calf, thou didst sacrifice thy sons to Baalpeor, thou didst defile the temple, thou didst go after every sort of vice, thou didst grow not to know nature itself. The mountains, the groves, the hills, the springs, the rivers, the gardens didst thou fill with accursed sacrifices, thou didst slay the prophets, didst overthrow the altars, didst exhibit every excess of wickedness and irreligion. Still, after giving thee up for seventy years to the Babylonians, He brought thee back again to thy former freedom, and gave thee back the temple, and thy country, and thy old form of polity and there were prophets again, and the gift of the Spirit.

[AD 418] Pelagius on Romans 11:10
This prophecy speaks of those who gave the Savior vinegar and gall to drink.

[AD 430] Augustine of Hippo on Romans 11:10
Behold mercy and judgment—mercy on the elect, who have obtained the righteousness of God, but judgment upon the others who have been blinded. And yet the former have believed because they willed it, while the latter have not believed because they have not willed it. Hence mercy and judgment were executed in their own wills.