Hi TheOne. I think what Andya was referring to was Sura 2, which discusses the relationship between Islam and Judaism/Christianity. There are a number of references, but one of the ones most germane (Andya can correct me if I'm wrong) is Sura 2:121 -
Those people to whom We gave AL-Tawrah and AL-Injil, who read their Book with careful scrutiny in search of truth, shall recognize what really proceeded from Allah and what has been adulterated by base admixture of false glosses. Such persons shall comprehend the truth and accordingly honour the Quran. And he who refuses to acknowledge the truth proceeded from Allah shall be an inherent loser. (Translation from the Egyptian Ministry of Al Awqaf, Supreme Council for Islamic Affairs on-line Quran).
As you can plainly see, the verse is talking about the Torah and Bible having been previously given to the Jews and Christians respectively, but then corrupted. The Quran in this case is clearly shown to be without the "adulteration" and "false glosses" put by fallible men into the previous two works. IOW, Allah had been there and done that with the other religions, and they botched the message. Third time's a charm, I guess, even for a deity.