This is an interesting variation on the legend of the Dancers of Kolbigk [spelling?]- where the dancers disturbed a priest saying mass, who cursed them to keep on dancing - some died, but some made it to a hermitage where they were shriven and forgiven. There's a big book on this somewhere. Tthe original gives a quote from their song:

Equitabat Bovo per silvam frondosam,
Et ducit [?] sibi Merswinden formosam.
Cur stamus? Cur non imus?

I think that's how it goes.