Many people do not understand whether they should use a colon or a comma before quotation marks, to introduce direct speech. In truth, it doesn’t really matter, and if you are introducing a quotation by using words such as “he said,” “she commented,” “they asserted,” etc. using either a comma before the quotation mark or a colon before the quotation mark is perfectly acceptable. However, as a guide, it is generally advisable that you use commas to introduce quotations that consist of less than seven words and colons to introduce anything longer than that:
He approached Jane and nervously asked, “Would you like to go out tonight?” (fewer than seven words, comma used)
The teacher shouted: “I will not ask you again to sit down and be quiet.” (More than seven words, colon used)
That said, the majority of writers punctuate direct speech according to their personal preferences and they often switch between using a colon or a comma before quotation marks. It is acceptable to introduce the quotation using either of the punctuation marks and it is common for people to use colons and commas interchangeably in the same document depending upon the length of the pause that is necessary before the direct speech commences.
Looking for further assistance with punctuation? Check out our free punctuation cheat sheet.