I respectfully disagree. I believe that knowing when and how to say "no" is one of the most important management skills, and I suspect that understanding the need to say "no" a lot more than "yes" in the early days of a project (or a whole business) is quite strongly correlated with success.
I think he meant to type "negotiation" rather than "negation", which makes little sense even if he was trying to convey the point you just made. So I was making a little fun of that. I agree with you.
