Prof. Muhammad Aliy Suglul stated that backbiting is one the great sins which Islam forbids. It is condemned in both the Qur’ān and the saying of the prophet, may Allah’s peace and blessings be upon him.

Allah, the most high, says: ‘O you who have believed, avoid much [negative] assumption. Indeed, some assumption is sin. And do not spy or backbite each other. Would one of you like to eat the flesh of his brother when dead? You would detest it. And fear Allah; indeed, Allah is Accepting of repentance and Merciful. [Quran 49 : 12 ]

Also, Allah says: ‘Woe to every scorner and mocker’ [Quran 104 : 1 ]

The scholars have explained it [the above verse] as booing or mocking others either through  statements or demonstration, for instance, use of eyes. 

Concerning entering the paradise (of the one who engages in it), As for entering Paradise, we do not find in the texts an explicit evidence on that.

As for how to atone for backbiting, that is by repentance. Some people may ask if it is compulsory to seek forgiveness of the victim, but the basis is to observe the consequences. If seeking the victim’s forgiveness after he had been informed will worsen the situation, there is no need to let him know. but will need to seek sincere forgiveness of Allah. There is no doubt that He erases sins, and multiplies good deeds. We must note that such act is connected to other people’s rights, hence, one must desist from it.