A little more digging, and success in uncovering
the source from which William Sharp / Fiona Macleod 's book
Pharais quoted the rune in the post before this one.

In fact, Sharp / Macleod cheerfully copied the prayer,
both in the original Gaelic and its English translation,
from a different presentation.
And as the bibliography shows, it predates Pharais.

Exactly as printed in the 1894 edition of Sharp / Macleod,
these first appeared in

Chapter 29, under the sub-heading,
"How an old Woman supposed to possess the Evil Eye escaped a cruel death", page 176, in
Nether Lochaber: the Natural History, Legends, and Folklore of the West Highlands, by the Rev. Alexander Stewart, F.S.A. Scot., Edinburgh: William Paterson, 1883.