Hilchos Lashon Hara, Opening – negative commands (17)
Sometimes one can also break the negative commandment (Vayikra 19:14), "Do not curse a deaf person." This happens if he speaks lashon hara about someone out of anger and then curses him. The verse means that one may not curse even a deaf person - and all the more so a person who is not deaf.
In total, we have counted seventeen negative commandments that a person can commonly break by speaking lashon hara.
All this is when he speaks in front of a Jew. If he speaks in front of a non-Jew, the sin is even greater, and he is called a "moser" (an informer).
Some of these sins bring death by the hand of Heaven, such as hurting a widow or an orphan. And some are connected to losing the World to Come, such as making another person's face go pale (embarrassing him), or gaining honor by putting another person down.