Authors:

The single and most dangerous word to be spoken in business is no. The second most dangerous word is yes. It is possible to avoid saying either.

"Company Manners: An Insider Tells How to Succeed in the Real World of Corporate Protocol and Power Politics". Book by Lois Wyse. Cited in "QFinance: The Ultimate Resource", p.1809, 2009.
The single and most dangerous word to be spoken in business is no. The second most dangerous word is yes. It is possible to avoid saying either.