Im(m)ram Brain (maic Febail) (The Voyage of Bran (son of Feba(i)l)). late Seventh/early Eighth Century AD (c AD 750):

Meyer, Kuno, ed and tr. The Voyage of Bran, son of Febal: An Old Irish Saga. London: David Nutt in the Strand, 1895.
https://ia802606.us.archive.org/18/items/voyageofbransono01scuoft/voyageofbransono01scuoft.pdf