Cyril of Alexandria

When the lawyer had answered the things contained in the law, Christ, to whom all things were known, cuts to pieces his crafty nets. For it follows, And he said to him, Thou hast answered right: this do, and thou shalt live.

Catena Aurea by Aquinas ↗

Theophylact of Ohrid

So, to the lawyer He says: "you have answered correctly." Since you, He says, are still subject to the Law, then you answer correctly; for according to the Law you reason rightly.

Commentary on Luke ↗

Bede

You have answered correctly: Do this, and you will live. Then, after introducing a parable responding that the one who showed mercy to the wounded was the neighbor, He adds: Go, and do likewise, that is, remember to love and support your neighbor who needs such mercy. Very clearly declaring that love alone, and not merely shown in word but proven by the execution of deeds, leads to eternal life.

On the Gospel of Luke ↗

Bonaventure

Thirdly, with regard to the approbation of the truth discovered, it is added: And he said to him: You have answered rightly: because you brought forth a word of rectitude, which pertains to love, according to that of Song of Songs 1: "The righteous love you"; or you spoke according to the rule of wisdom, according to that of Proverbs 8: "All my words are just, there is nothing crooked or perverse in them; they are right to those who understand and equitable to those who find knowledge." And because one must live according to the rule …

Commentary on Luke, Chapter 10 ↗