Augustine of Hippo

It was brought about, I conceive, by God's providence, that the Saviour's price should not minister means of excess to sinners, but repose to foreigners, that thence Christ might both redeem the living by the shedding of His blood, and harbour the dead by the price of His passion. Therefore with the price of the Lord's blood the potter's field is purchased. We read in Scripture that the salvation of the whole human race has been purchased by the Saviour's blood. This field then is the whole world. …

Catena Aurea by Aquinas ↗

Jerome

However, with a plan devised, they bought a field from that potter, for the burial of strangers, therefore that field was called Acheldemach, which means the field of blood, to this day. Indeed, they acted with a different intention, that they might leave a lasting monument of their impiety from the purchase of the land. But we, who were strangers to the Law and the prophets, have embraced their corrupt practices for salvation: and we find rest in the price of his blood. …

Commentary on Matthew ↗

Thomas Aquinas

Then he narrates what was done with it. And first he states the deed; secondly, what came of it. He says: "and after they had consulted together etc." Why did they do this? It must be said that God so arranged it, that this deed should be kept in memory. Hence they bought with them the potter's field, to be a burying place for strangers, not for those who were of the country, but for foreigners. …

Commentary on Matthew ↗