"And I quote …"
In talks or speeches it is usually helpful (maybe even necessary) to preface a quotation with the words "and I quote" in order to distinguish clearly the words of the speaker from those of the person being quoted.
However, "and I quote" is unnecessary in written pieces, since the quotation marks are an adequate indicator of the fact that the words to follow are verbatim those of the person being quoted.
So, for example, it is sufficient to write: "When Nelson Mandela visited our city he said, 'We must strive to give expression to our unity.' It is unnecessary to write: "When Nelson Mandela visited our city he said, and I quote: 'We must …'" -ws-