John Chrysostom

There are two gifts of God which he here points out. The "freeing from sin," and also the "making them servants to righteousness," which is better than any freedom. For God hath done the same as if a person were to take an orphan, who had been carried away by savages into their own country, and were not only to free him from captivity, but were to set a kind father ever him, and bring him to very great dignity. And this has been done in our case. …

Homily on Romans 11 ↗

Theophylact of Ohrid

Two, he says, benefits you received from God: you were both freed from such dishonor and became servants of righteousness, which constitutes great glory for you.

Commentary on Romans ↗