Cyril of Alexandria

And since he tempted Him subtly, he receives no other answer than the command given by Moses; for it follows, He said unto him, What is written in the law? how readest thou?

Catena Aurea by Aquinas ↗

Ambrose of Milan

With these verses belongs the text that exposes those who seem to themselves to be experts on the law, who keep the letter of the law but disregard its spirit. He teaches that they are ignorant of the law from its very first chapter. He proves this immediately at the beginning of the law. …

Commentary on Luke ↗

Bede

But he said to him: What is written in the law? How do you read it? He answered, saying: You shall love the Lord your God with all your heart, and with all your soul, and with all your strength, and with all your mind, and your neighbor as yourself. As the lawyer responds, our Savior shows us the perfect path to heavenly life. To the one proposing the writings of the law about the love of God and neighbor, He says:

On the Gospel of Luke ↗

Bonaventure

Second, regarding the discovery of the truth sought, he adds: But he said to him: What is written in the Law? How do you read? From this it is apparent that the Master of truth was a friend of the Law, according to Matthew five: "Do you think that I have come to abolish the Law or the Prophets? …

Commentary on Luke, Chapter 10 ↗