What is the ruling on sitting with someone who backbites, when one does not know whom he means, and is it obligatory to denounce that and advise him?

Backbiting is forbidden, and whoever hears someone backbiting another must advise them and warn them of its danger. If the person does not comply, it is obligatory to leave that gathering and not listen to thebackbiting, even if the victim of the backbiting is not known. The listener must condemn it in their heart and leave the gathering if possible. If they cannot leave, they should remember Allah or think about something else to distract themselves from listening.