If such a phrase contains more than one preposition, a comma may be used unless a verb immediately follows the phrase. Other writers do not put a comma before quotations unless one would occur anyway. Thus, they would write "Mr. Kershner says 'You should know how to use a comma.'" https://springkasteelgenk82555.ttblogs.com/17823153/unicorn-springkasteel-huren-voor-dummies