It's:
"Cold be hand and heart and bone
And cold be travelers far from home
They do not see what lies ahead
When sun has failed and moon is dead."

It's half of a song that was written by Fran Walsh and translated in Sindarin.
The full song in English is:

"Cold be hand and heart and bone
And cold be travellers far from home
They do not see what lies ahead
When sun has failed and moon is dead.
In the black wind the stars shall die,
On this bare earth here let them lie,
Till the dark lord lifts his hand
Over dead seas and withered land."

And the translation into Sindarin of the full song is:

"No ring cam a hûn ah asg
A no ring randir chaer o mbar
Ú-genir i lû i caeda na nîf
Ta i pellen anor a firnen ithil.
Vi gwae’ vorn elin firithar
Bo cae lanc hen sí caedathar
Tenn i vorchir gam în ortha
Or aerath firnin a dôr tharn."

You can also hear part of it sung in Sindarin on the TTT soundtrack. Taming of Sméagol - track 2. Around 30 seconds in...

It's based upon a song from Book 1, Chapter 8, Fog on the Barrow-downs.

Cold be hand and heart and bone,
and cold be sleep under stone:
never more to wake on stony bed,
never, till the Sun fails and the Moon is dead.
In the black wind the stars shall die,
and still on gold here let them lie,
till the dark lord lifts his hand
over dead sea and withered land.


I spend waaaaaaaaaaaaaay too much time researching the lyrics and poems in the films...