In indirect talk, we say: -- ABC dice di {no,si}, where ABC is a person or a pronoun, or a different subject as in: -- la pioggia dice di no alla nostra gita nel bosco. In direct talk, when reporting (quoting) the speech of somebody else obviously /di/ should NOT be present: Example from an imaginary book: a) hai chiesto a Giovanni ? b1) Glie l'ho chiesto un'ora fa al telefono, ha detto "no" b2) Glie l'ho chiesto un'ora fa al telefono, ha detto di no. When what is reported above HAPPENS in true life, (in a talk) there is ABSOLUTELY NO HINT that (b1) uses quoting, as the reported sentence ("no") is too short to make the quotes magically 'appear' while speaking (in longer quoted sentences the syntax pattern of the quoted sentence will reveal the quotes). This is the reason why both forms are fine and accepted when speaking and we lost in some way the distinction between them, and why the form with /di/ is more 'rounded', as usually in conversation we don't use quoting, but reporting others opinions. As a

Thank you all for your answers. It just shows that learning vocabulary and rules of grammer without learning the subtleties of usage only gets you part way to the goal!

Hi Fred, good question:) As Elia told you ,I think you can say both ways ' Lui dice di no' or 'Lui dice no'.I prefer the first one ,but when I asked my husband 's opinion,he prefered the second one! :)

It's really hard to say, lui dice di no sounds way better but I don't think it is a mistake if you leave di out.

*questa