John Chrysostom

"Having raised up": again, the Resurrection. "In turning away," he says, "every one of you from his iniquities." In this way He blesses you: not in a general way. And what kind of blessing is this? A great one. For of course not the turning a man away from his iniquities is itself sufficient to remit them also. And if it is not sufficient to remit, how should it be to confer a blessing? For it is not to be supposed that the transgressor becomes forthwith also blessed; he is simply released from his sins.

Homily on Acts 9 ↗

Theophylact of Ohrid

"Jesus," whom God, "having raised up… sent to you first… to bless you." God sent Him to other nations as well, but to you, who crucified and killed Him, He sent Him first. When? Only from the cross? No, even after that, and after the resurrection. To do what? "To bless you" and save you, if you yourselves truly desire to turn away "from your evil deeds."

Commentary on Acts ↗

Bede

To you first (he says) God, raising up His Son. Here it should equally be noted that it is concerning the same Son of God, whom he calls the seed of Abraham, due to the twofold nature of Christ, lest they believe Christ to be merely a man, or one son human and the other divine. By this snare of heresy, the insane Manes and Nestorius were deceived.

Commentary on Acts ↗