The Gaelic text Auraicept na n-Éces “The Scholars’ Primer” was attributed by tradition to the Irish scholar Cenn Faélad († 679). Besides this tract, dealing with language, he was also supposed to have composed legal poems and been the head of a monastic Latin school.
The following text was translated by Michael Newton from the edition in Ahlqvist, The Early Irish Linguist, 47-8.
Gaelic authorities say that a marvelous and unusual feat – the building of Nimrod’s tower [the Tower of Babel] – caused the invention of the language of the Féni [i.e., Gaelic]. […] Fénius Farrsaid invented it ten years after people left the tower; each fellow-speaker [of Gaelic] went to settle territory [together], regardless of his original kin-group affiliation. This was true of Cai Caínbrethach [“Fair-judgment”], the fosterling/student of Fénius Farrsaid, who was the 72nd disciple of the school; he had Jewish ancestry and he went to Egypt. Fénius himself lived at the Tower until the school asked him to create a language unique to them from the many different languages. It was assigned to one of them: Goidelic is named from Góedel of the Greeks. […] Whatever was the best of every language, whatever was most expansive and finest, was put into Gaelic.