I have a transcription of this song as sung by Joe Heaney from the University of Washington. As a caveat, I admit that he may have got his version from Seamus Ennis. Also, I don't know if he assisted the transcription in any way.

In any case, the chorus is offered as:

Abair-a-linn, abair-a-linn

Say it to us, say it to us

Brían.