(Verse 24, 25.) On that day, Israel will be a third, along with Egypt and Assyria, a blessing in the midst of the earth. The Lord Almighty will bless them, saying, 'Blessed be Egypt my people, Assyria my handiwork, and Israel my inheritance.' In no way will Israel be a mediator between Egypt and Assyria, now that Antiochus and Demetrius are drawing the kingdom to themselves, now that the Ptolemies are claiming its possession for themselves. But even under Roman rule, and therefore under the rule of Christ, it will be of the same condition as Egypt and Assyria, and it will be blessed in all the earth. Because the law will go forth from Zion, and the word of the Lord from Jerusalem. Then it will be said by the Lord: Blessed is my people of Egypt: when by no means Moses, but Christ the Lord leading the way, the countless thousands of men have filled the wilderness, and with Pharaoh submerged, they have said in the desert: Let us sing to the Lord, for He has been gloriously magnified: He has cast horse and rider into the sea (Exodus 15:1). Then the work of the Lord will also reign in Assyria; for these are the largest nations of monks, Egypt and Mesopotamia, and they contend with each other in equal piety. But the inheritance of Christ is the Israel, that is, the places of his birth, and the cross, and the resurrection, and his ascension, to which people from all over the world gather.
[AD 420] Jerome on Isaiah 19:24-25