Is seeking forgiveness (istighfar) alone sufficient for repentance from backbiting if the virtues of the one backbitten are not known, and what is obligatory in this case? And is the repentance of the listener to backbiting like the repentance of the one who spoke it, based on the school of thought that says the expiation for backbiting is seeking forgiveness for the one backbitten and mentioning their virtues?

We have previously explained the nature of repentance from backbiting, which is to seek forgiveness from the wronged person in general, as long as no greater harm is feared. There is no need to detail the backbiting, along with mentioning the backbiting person with good and seeking forgiveness and supplicating for them.

The mentioned hadith is not authentic, as it has been weakened by Al-Bayhaqi, Al-Busiri, Al-Sakhawi, Al-Albani, and others.

If a person does not know of any good qualities for the one they backbit, then their acceptance of Islam is the greatest of good qualities, and likewise, prayer and other deeds can be mentioned regarding them.

Listening to backbiting is forbidden, and we have previously explained the nature of repentance from it.