Would that be this one?

In the land of Odin there stands a mountain,
that reaches a hundred miles in the air.
From edge to edge, that sacred mountain,
measures one thousand miles square.

A little bird comes wingin'
once every million years
to sharpen its beak on that mountain
and then quickly disappear,
for another million years.

And when that mountain shall be all worn away,
that, to eternity, shall be -- one single day...