It is sung in Welsh by Miranda, Glen, Geraint Jones, Rachelle Eves and Tony Glen.
Here is the English translation:
A Pure Heart
I don't ask for a luxurious life
The world's gold or its fine pearls,
I ask for a happy heart,
An honest heart, a pure heart.
A pure heart full of goodness
Is fairer than the pretty lily,
None but a pure heart can sing,
Sing in the day and sing in the night.