President Obama says, "It's no secret that those of us here tonight have had our differences over the last two years. The debates have been contentious; we have fought fiercely for our beliefs." The line above contains an example of a(n)
The line is an example of a direct quotation. That is when a quotation by someone is unchanged and presented in its entirety. Of course, it's a part of a larger speech, but it's unchanged and can be as such analyzed for various things that the linguists would be searching for.
Due to the sentence not only including quotation marks but also the individual who stated this, the above statement would be an example of a direct quotation.