Bede

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 …

Commentary on Ezra and Nehemiah ↗