Marion Zimmer Bradley's The Forest House is a lose retelling of Belini's opera Norma. Several hymns were taken from the opera verbatim, something done as tribute to the source material. Zimmer Bradley states all this in a short author's note in the beginning of the novel. As @CrisSunami states in a comment, this is common practice. The author's note can be located in the beginning or the end.
However, it is important to note Norma is in the public domain. The situation is somewhat different for texts which are still copyrighted, as @Amadeus states.
In such a case, you would need to obtain permission from the author to use his text. Write to the relevant copyright holder, get the permission. Unless you're putting the thing in very negative context, it's extra publicity for them. That's always good. As an example, in the Acknowledgements section of Olympos, Dan Simmons writes:
I would like to thank Jean-Daniel Breque for his permission to use the details of one of his favourite walks down the avenue Daumesnil and the rest of that Promenade Plantée. A full description of this delightful walk can be found in Jean-Daniel's essay "Green Tracks" in the Time Out Book of Paris Walks, published by Penguin.
Note that in this case nothing is quoted verbatim, but nonetheless permission has been obtained, and credit is given. This is not to say that a verbatim quote could not have been used.
It is for you to find out whether the work you wish to quote is copyrighted, and to obtain permission to use it if it is. Then, just provide accreditation in the beginning or the end.