The Strasbourg Oaths were recorded in 14 February 842. Because they include a version in French they are considered the first documents to be written (in part) in French. If they were written in Brithenig the result would have been something like this:
Per afur Dew e per salyd ill pobl cristian e nu thud, di'll diwrn ci inawant, in cant Dew mi ddun saber e boder, sig eo salwarai yst mew ffradr Carol, sig yn of def salwar sew ffradr di'll druith, in o ke ys ffag allarn e cun Loteir eo ngwen nonc cun yn plegid ke di few wolont bod esser dawnus a few ffradr Carol.
For the love of God and for the salvation of Cristian people and us all, from this day forward, in so far as God gives me knowledge and power, I will support this my brother Charles, as one should support his brother by right, provided that he does likewise to me, and I will never take an arrangement with Lothair that of my will may be harmful to this my brother Charles.