It makes them full of understanding, like the Euphrates: Revised Standard Version has inserted the pronoun them; it is not in the Greek. As in verse 25a, Good News Translation is closer to the meaning here: “The Law brims over with understanding.” The Euphrates River rises in Turkey, flows across Syria and down most of the length of Iraq, south of the Tigris River, until joining the Tigris.

And like the Jordan at harvest time: Harvest time is again a reference to the spring.

An alternative model for this verse is:

• It [the Law] brims over with understanding just like the Euphrates and Jordan rivers overflow with water during the spring harvest.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on Sirach. (UBS Helps for Translators). New York: UBS, 2008. For this and other handbooks for translators see here.