Dreaming of being with people who slander is a warning this will create problems and serious consequences. Dreaming of defaming someone is a subconscious warning that you should not do it, because of the dangers it contains. Dreaming of being slandered by friends, who you considered to be sincere, indicates that in reality you do not trust those around you (employees, servants, etc.).
Read more about dreaming of Defamation in other dream meanings interpretations.