Assalam o Alaikum!
Most of people among us are consider their self completely secure from sin but the major fact is that no one is save and secure completely while he or she does not consider on their basic and common mistakes.
Basic and common mistakes are in my point of view is that if a person offers five times prayers and recite The Holy Quran and even he sits in the Mosque (Masjid) and their he cannot do any sin because he is in the house of ALLAH Almighty, but one sin he or she has that they do in the Mosque (Masjid) and they also do not know that when did they do this sin, this grave sin is done by them even in the house of ALLAH Almighty, it is called Back Biting and mostly people are habitual to do this job as a rule and even if they do not do this then they feel that they do not have good topics to discuss that is why they do this grave sin in the shape of their interesting and spicy topics and bundle of grave sin they make.
Have we ever thought about our this habit? Is it true that this habit is found in us? If this is true then hurry up and be conscious and make (tauba) and also ask for forgiving that person that was criticised in your topics then you might be save from the (azaab) of the hell fire.
There are various hadith on this Grave sin, and the major point is that Back Biting is bigger sin than Fornication, now think that how serious this sin is.
The Prophet (Peace be upon him) said: If you do back biting of anyone it means that you eat their meat, let we share some authentic hadith with references.
Narrated by Anas ibn Malik(Radhiallaho anho):
Allah's (sallAllaahu `alaihi wasallam) said :When I was
taken up to heaven I passed by people who had nails of copper and
were scratching their faces and their breasts. I said: Who are these
people, Gabriel? He replied: They are those who were given to back
biting and who aspersed people's honour.
(Sunan of Abu-Dawood 4860)
There are various Hadith about backbiting but i think for those people who believe on the (day of judgment) this Hadith and paragraph is enough for them.
Keep yourself away from this Grave sin and save others from this Grave sin.