John Chrysostom

Therefore when Christ said, "If thou wilt enter into life, keep the commandments," he saith, "Which?" Not tempting, far from it, but supposing there were some others besides those of the law that should procure him life, which was like one who was very desirous.

Homily on the Gospel of Matthew 63 ↗

Jerome

But if you want to enter life, keep the commandments. He said to him, 'Which ones?' Jesus replied, 'You shall not murder. You shall not commit adultery. You shall not steal. You shall not give false testimony. Honor your father and mother, and love your neighbor as yourself.' This young man is tempting, and from this we can prove that when the Lord tells him, 'If you want to enter life, keep the commandments,' he deceitfully asks what those commandments are: as if he himself had not read them, or as if the Lord could …

Commentary on Matthew ↗

Hilary of Poitiers

This young man has grown impudent from studying the law. He is worried about his salvation. Jesus sends him back to the law so that he might understand that, in the very thing in which he takes pride, he has as yet done no righteous work. For the Lord answered him with the words of the law. But the young man, like the boastful and impudent people of whom he is a type, put his trust in the law, but he did not really comply with it at all. For they had been ordered not to kill, yet they had killed the prophets. …

Commentary on Matthew 19.5 ↗

Thomas Aquinas

He said to him: which? There follows the exposition of the response, in which he recounts the commandments. And first he sets forth the commandments; secondly the root, at you shall love your neighbor as yourself. He says therefore Jesus said: you shall not kill etc. And why does he not mention the commandments of the first table? Because he saw him inclined to the love of God; therefore it was not necessary. Likewise these are preliminary to love. And first he sets forth the negative; secondly the affirmative. …

Commentary on Matthew ↗