"Whenever you can, take material from the original source, not a secondhand one. Sometimes, however, only an indirect source is available -- for example, an author's published account of someone's spoken remarks. If what you quote or paraphrase is itself a quotation, put the abbreviation qtd. in ("quoted in") before the indirect source you cite in your parenthetical reference." [taken from MLA Handbook. 8th ed., MLA, 2016, p. 124.]
Include the SECONDHAND source in your Works Cited list.
In text citation:
Hillary Clinton says many of our health-care problems “will only continue to get worse” (qtd. in Fallows).
Works Cited entry:
Fallows, Michael. "A Triumph of Misinformation." The Atlantic, Jan. 1995, http://www.theatlantic.com/magazine/archive/1995/01/a-triumph-of-misinformation/306231/.