Sir Orfeo

Sir Orfeo is a magical confection, a medieval resetting of the classic tale of Orpheus and Euridyce as the quest of King Orfeo to reclaim his wife Lady Heurodis from the realm of the King of Faery. The story is preserved in three Middle English manuscripts of the fourteenth and fifteenth centuries, based on a lost Breton lyric lay, and in the Shetlandic folk-ballad King Orfeo.
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The tale of Sir Orfeo - or Sir Orpheus - occurs in a manuscript written in about 1330-1340 in a London scriptorium and known famously as the Auchinleck Manuscript, in which is also found the tale of Sir Degaré. It now lies in the National Library of Scotland as Manuscript Advocates 19-2-1 and is thought by some to have been owned once by Geoffrey Chaucer. The tale retells the ancient Greek story of Orpheus's attempted rescue of his wife Eurydice from Hades; and in this case, involving the Celtic Otherworld, the rescue proves successful.
(The tale of Sir Orfeo)

A just and noble king, Orfeo, once reigned over a small kingdom. His holdings were prosperpous and his people dwelt in comfort and unassailed by outside foes.
In these joyful and peaceful times, King Orfeo had time to pursue many courtly interests, but he was especially skilled at the harp. Indeed, such was his skill that the harmonious existence in Orfeo's kingdom was due--in part--it was said, to the exquisite harmonious melodies flowing from his harp.
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Link: Weirdletter, Internet Archive, King Orfeo in modern english, King Orfeo. A Shetland Ballad.