Green Speech #26:
When speaking Loshon Hara- ( Words & Speech that are derogatory, hurtful, damaging and gossip)
You compound the resulting ill-effects of your speech by causing others to listen to the Loshon Hara. Jewish wisdom teaches us that there is not only a prohibition against speaking to Loshon Hara but listening to it as well.
When you speak Loshon Hara you also transgress another prohibition "Do not place a stumbling block before the blind" by causing others to listen to the Loshon Hara. - they transgress by listening you compound your transgression by making someone else listen to Loshon Hara.
The more listeners present, the more sins one commits. If, for example, a person speaks at a table where five people are present, then the violation of “Do not place a stumbling block before a blind man” is multiplied by five.