Buile S(h)uib(h)ne (The Madness of Sweeney, or Sweeney’s Frenzy). Twelfth Century AD, possibly as early as Ninth Century AD:

O’Keeffe, James George, ed and tr. Buile Ṣuiḃne. (The Frenzy of Suibhne) being The Adventures of Subhne Geilt, a Middle Irish Romance. London: David Nutt, 1913.
https://ia801702.us.archive.org/25/items/builesuibhnethef12okee/builesuibhnethef12okee.pdf