"Superstitions about changelings and fairy abductions underline the theme of the song, ‘Seo hu leo’, or, as it is more commonly called, ‘A bhean ud thíos’. The song was written down by George Petrie from the singing of Mary Madden, a poor blind country woman from County Limerick but then resident in Dublin, and it was published by him in his ‘Ancient Music of Ireland’[1855]."

Petrie was not a fluent Irish speaker, but was assisted by Eugene O’Curry. To read O'Curry's commentary on the song, see: https://www.clarelibrary.ie/eolas/coclare/music/petrie_and_music_of_clare2.htm>
https://www.clarelibrary.ie/eolas/coclare/music/petrie_and_music_of_clare2.htm from "Petrie and the Music of Clare" by Breandán Breathnach
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This song is a lullaby, but it appears that the song is set as a lullaby so the fairies won't realise that the woman singing is telling her husband how to rescue her from abduction by the fairies.

https://www.folkradio.co.uk/2021/11/video-lorcan-mac-mathuna-a-bhean-ud-thios/
"In Irish folklore, the fairies represent the opportunity and danger of the unknown. We find that fairies are an enigma that are beyond our reach for the most part but have the ability to pass through the veil that separates the supernatural from the mortal realms. They are vicarious, contrary, hard to predict, and frequently are blamed for misfortune.

"Fairies, it is said, steal children for their grieving women folk, and will steal young women for brides or nursemaids. In the Song, A Bhean Úd Thíos, a young bride, taken into the fairy Rath, tries to communicate with a washer woman with a message for her husband who she has been separated from for a full year. Her imploration finishes with a surprising subversive line.

“ 'For if he come not then, he need come never,
For they’ll make me Fairy Queen forever!' ”

A BHEAN ÚD THIOS

A bhean úd thíos, air bhruach an tsrutháin
Seóthú leó, seóthú leó
An dtuigeann tusa fáth mo ghearáin?
Seóthú leó, seóthú leó
S'é bliain is lá inniu ó fuadaíodh mé óm leannán
Seóthú leó, seóthú leó
Is go rugadh isteach mé i Lios a Cnocáin
Seóthú leó, seóthú leó

Curfá:
Seoithín, seoithín, seoithín, seoithín, seoithín seó uil leo leo,
Seoithín, seoithín, seoithín, seoithín, seoithín seó uil leo leo.

Seo é anseo mo theach mór maiseach
Seóthú leó, seóthú leó
Is mo leann úr agus seann leann ann
Seóthú leó, seóthú leó
Mo mil bhuí agus céir bheach ann
Seóthú leó, seóthú leó
Agus mo sheanduine air a nasc ann
Seóthú leó, seóthú leó

Abair le m' chéile teacht amárach
Seóthú leó, seóthú leó
'S an coinneal chéireach i gcroí a dhearnáin
Seóthú leó, seóthú leó
Scian choise duibhe a thabhairt na láimh leis
Seóthú leó, seóthú leó
S' an capall tosaigh a bhualadh sa bhearna
Seóthú leó, seóthú leó

An luib a bhuaint, tá i ndoras a leasa
Seóthú leó, seóthú leó
Mar shúil le Dia go rachainn leis abhaile
Seóthú leó, seóthú leó
No mura dtaga sé faoin tràth sin
Seóthú leó, seóthú leó
Go mbeidh mé im bhanríon air na mná seo
Seóthú leó, seóthú leó

Translation

oh woman below on the brink of the stream,
Sho hoo lo, sho hoo lo
Do you understand the cause of my wailing
Seóthú leó, seóthú leó
It's a year and a day since I was abducted from my darling
And carried into the fairy hillfort

chorus=
Shoheen, shoheen, shoheen, shoheen, shoheen, show uil lo low
Seoithín, seoithín, seoithín, seoithín, seoithín seó uil leo leo.

Here is my great beautiful house
There is abundant ale there, fresh and aged/old and new
Abundant yellow honey and bees wax
And many an old man tightly bound there.

Tell my husband to come tomorrow
With the wax candle in the centre of his palm
And in his hand bring a black-handled knife
And to strike the first horse out of the gap.

To pluck the herb that's in the door of the fort
With trust in God that I would go home with him.
For if he doesn't come within this time
I will be made queen over all these women. [and not return]

sheet music and ABC, source Dónal O' Sullivan Songs of the Irish https://abcnotation.com/tunePage?a=ifdo.ca/~seymour/runabc/esac/IRL/0032

Some recordings
https://archive.culturalequity.org/field-work/ireland-1951-and-1953/macroom-i-151/bhean-ud-thios Elizabeth Cronin

Alan Lomax interviewing Elizabeth Cronin about A Bhean Úd Thíos

Lorcan Mac Mathúna

Mary McLaughlin