Remigius of Auxerre
Catena Aurea · Matthäusevangelium 1
Now all this was done, that it might be fulfilled which was spoken of the Lord by the prophet, saying, Behold, a Virgin shall be with child, and shall bring forth a Son, and they shall call His Name Emmanuel, which being interpreted is, God with us.
It is the custom of the Evangelist to confirm what he says out of the Old Testament, for the sake of those Jews who believed on Christ, that they might recognize as fulfilled in the grace of the Gospel, the things that were foretold in the Old Testament; therefore he adds, Now all this was done.