To dream of back-biting about someone, warns that you will cause harm to someone if you do not stop whatever you may be doing. Think twice over your actions and its consequences.
To dream that someone is back-biting you, signifies that you will have some family problems.
To dream of back-biting, (creating malicious gossip), about someone means you will soon fall into serious error if you do not halt whatever you may be doing that may harm someone. To have someone back-bite you means you will have problems with family and/or children.