Can you solve it?

[Abissor Swordzenorbe]

Of course it is mountain, because it's famous riddle from Hobbit book and for precise it's "Riddle Duel" beetween Bilbo Baggins and Gollum/ Smeagol.

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They are dark words, which cover the truth,
if you uncover it you will in danger too,
but if you find out what is it,
you must tell about it to trusted man.
Beware young man it's hard to know,
who will be your friend after this
and who even so.
But if you find trusted person and tell about it to him,
there's not turning back from this moment and you must take responsible of you two.

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What's answer to my riddle ?????