King Herla

An ancient British king is attends a fairy wedding for three days, and on his return finds centuries have passed. He and his men are doomed to ride eternally. never touching the ground for fear of turning to dust.
From Walter Map:

One court and one only do stories tell of that is like our own.
A king of the most ancient Britons, Herla, it is said, was on a time interviewed by another king who was a pygmy in respect of his low stature, not above that of a monkey. This little creature was mounted on a large goat, says the tale, and might be described in the same terms as Pan; his visage was fiery red, his head huge; he had a long red beard reaching to his chest, which was gaily attired in a spotted fawn’s skin: his belly was hairy and his legs declined into goats’ hoofs.
Herla found himself tete-a-tete with this being, who said: “I am the king over many kings and princes, an unnumbered and innumerable people, and am sent, a willing messenger, by them to you. I am unknown to you, it is true, but I glory in the renown which has exalted you above other monarchs, inasmuch as you are a hero and also closely connected with me in place and descent, and so deserve that your wedding should be brilliantly adorned by my presence as a guest, so soon as the King of the Franks has bestowed his daughter upon you. This matter is being already arranged, though you know it not, and the ambassadors will be here this very day. Let this be a lasting agreement between us, that I shall first attend your wedding and you mine on the same day a year hence.”
With these words, swifter than a tiger, he turned and vanished from view. The King returned home struck with wonder, received the ambassadors and accepted their proposals. When he took his place in state on the wedding day, before the first course the pygmy made his appearance, with so vast a crowd of similar beings that the tables were filled and a larger number sat down to meat outside the hall than within it, in pavilions brought by the pygmy, which were set up in a moment of time. Out of these pavilions darted servants bearing vessels each made of a single precious stone, by some not imitable art, and filled the palaces and the tents with plate of gold and jewels; no food or drink was served in silver or wood. Wherever they were wanted, they were at hand: nothing that they brought was from the royal stock or elsewhere; they lavished their own provision throughout, and what they had brought with them more than satisfied the utmost wishes of all. Nothing of Herla’s preparations was touched: his own servants sat with their hands before them neither called for nor offering aid. Round went the pygmies, gaining golden opinions from everyone: their splendid clothing and jewels made them shine like burning lights among the company: never importunate, never out of the way, they vexed no one by act or word.
Their King, while his servants were in the midst of their business, addressed King Herla in these terms: “Noble King, I take God to witness that I am here present at your wedding in accordance with our agreement. Yet if there be anything more of your contract than you see here that you can prescribe to me, I will gladly supply it to t}:ie last point; if there be nothing, see that you do not put off the repayment of the honour conferred on you when I shall require it.” And so, without awaiting a reply, he swiftly betook himself to his pavilion, and about cock-crow departed with his people.
After a year had passed, he suddenly appeared before Herla, and called on him to fulfil his agreement. To this he consented, and after providing himself with supplies sufficient for an adequate repayment, he followed whither he was led. The party entered a cave in a high cliff, and after an interval of darkness, passed, in a light which seemed to proceed not from. the sun or moon, but from a multitude of lamps, to the mans10n of the pygmy. This was as comely in every part as the palace of the Sun described by Naso.
Here the wedding was celebrated, the pygmy’s offices duly recompensed, and when leave was given, Herla departed laden with gifts and presents of horses, dogs, hawks, and every appliance of the best for hunting or fowling. The pygmy escorted them as far as the place where darkness began, and then presented the king with a small bloodhound to carry, strictly enjoining him that on no account must any of his train dismount until that dog leapt from the arms of his bearer; and so took leave and returned home.
Within a short space Herla arrived once more at the light of the sun and at his kingdom, where he accosted an old shepherd and asked for news of his Queen, naming her, The shepherd gazed at him with astonishment and said: “Sir, I can hardly understand your speech, for you are a Briton and I a Saxon; but the name of that Queen I have never heard, save that they say that long ago there was a Queen of that name over the very ancient Britons, who was the wife of King Herla; and he, the old story says, disappeared in company with a pygmy at this very cliff, and was never seen on earth again, and it is now two hundred years since the Saxons took possession of this kingdom, and drove out the old inhabitants."

The King, who thought he had made a stay of but three days, could scarce sit his horse for amazement. Some of his company, forgetting the pygmy’s orders, dismounted before the dog had alighted, and in a moment fell into dust. Whereupon the King, comprehending the reason of their dissolution, warned the rest under pain of a like death not to touch the earth before the alighting of the dog.
The dog has not yet alighted.
And the story says that this King Herla still holds on his mad course with his band in eternal wanderings, without stop or stay. Many assert that they have often seen the band: but recently, it is said, in the first year of the coronation of our King Henry, it ceased to visit our land in force as before. In that year it was seen by many Welshmen to plunge into the Wye, the river of Hereford. From that hour the phantom journeying has ceased, as if they had transmitted their wanderings to us, and betaken themselves to repose.
Walter Map, De Nugis Curialium, trans. M.R. James, revised C.N.L. Brooke and R.A.B. Mynors (Clarendon Press, Oxford, 1983), p27-31