In a Celtic folktale where many witches enter a house and ask the mistress of the house to prepare cake for them, whose advice helps the mistress get rid of the witches?

Advice of saying three time that 'The mountain of the Fenian women and the sky over it is all on fire'

Explanation:

The witches order the woman to fetch water from the well in the sieve so as to use if for the cake.

When the woman is unable to draw water from the well,a voice in the well asks her to bid yellow clay with moss and plaster the sieve with it so it will hold.

She does and then the voice asks her to enter the house from North and scream thrice 'The mountain of the Fenian women and the sky over it is all on fire'.

The witches immediately run away to their secret abode.