16 We certify the king that, if this city be builded again, and the walls thereof set up, by this means thou shalt have no portion on this side the river.
We announce to the king, that if that city is built, etc. He names the Euphrates river, within which is Syria. Which rightly indicates the stream of holy baptism, either because it is one of the four rivers which, rising from one source in paradise, irrigate the whole world; indeed in the figure of the four evangelists, who, inspired by the one source of life, that is, the Lord Savior, proclaim with a harmonious voice to all nations the washing of salvation; or because Euphrates is interpreted as fruitful; which name most aptly fits that sacrament by which the world, washed and sanctified, customarily brings forth the fruit of souls thirtyfold, sixtyfold, and a hundredfold to God. Therefore, the king of the Persians, who are interpreted as tempters, seeks possession beyond the river, when the ancient enemy, by stirring up the incursions of temptations, tries to break into the boundaries of the Church, and to subjugate to himself even those who are redeemed by the sacred font. The Samaritans help him, as heretics who attack the Church fight for the kingdom of the devil, and as if they are said to be grieving: Because if that city is built, and its walls restored, through true faith and the religious works of the righteous, he will not be able to have possession and place beyond the river, that is, in the hearts of those who are already reborn to God through baptism. They are also understood who do not understand the true faith, that one and the same mind cannot be possessed by light and darkness, iniquity and justice, Christ and Belial.
[AD 735] Bede on Ezra 4:16