In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Al-Allaamah Saalih Al-Fawzaan [may Allaah preserve him] stated: And the worst (of the tale-carriers) is that one who hastens to destroy the relationship between the students of knowledge and the callers to Islam, split the Jamaa’ah of the Muslims and incite hatred between them. The one who does this is a Nammaam (a tale-carrier). Indeed, Allaah [The Most High] forbade (us) from following and believing such a person even if he swears by Allaah, as Allaah said:
وَلَا تُطِعۡ كُلَّ حَلَّافٍ۬ مَّهِينٍ
هَمَّازٍ۬ مَّشَّآءِۭ بِنَمِيمٍ۬
And obey not everyone who swears much, and is considered worthless, a slanderer, going about with calumnies.
The Prophet [peace and blessings of Allaah be upon him] said: “The tale-carrier will not enter paradise”. Wars may occur due to the Tale Carrier, the Muslims may split and show enmity to one another due to the Tale Carrier, neighbours may boycott one another and one’s household may show enmity to one another and split due to a tale-carrier. Therefore, we must fear Allaah [The Mighty and Majestic] and be mindful of the tale-carrier. (1)
Imaam Abdul Azeez Bin Baaz [may Allaah have mercy upon him] said: This is a threat against the tale carrier. If he is a person upon Tawheed, it is hoped that he will enter paradise, but it is feared that this sin [i.e. tale carrying] will prevent him from entry into paradise for some time and enters him into the hell fire for some time, just as it is case with all other sinners. The sinners [i.e. those who die whilst committing sins lesser than shirk] are under the will of Allaah- if Allaah wishes, He will either punish them or forgive them straight away, or He enters them into hell for some time and paradise thereafter, just as Allaah said: [ إِنَّ ٱللَّهَ لَا يَغۡفِرُ أَن يُشۡرَكَ بِهِۦ وَيَغۡفِرُ مَا دُونَ ذَٲلِكَ لِمَن يَشَآءُۚ – Verily, Allah forgives not that partners should be set up with him in worship, but He forgives except that (anything else) to whom He pleases]. [Surah An-Nisaa’ Aayah 48] (2)
Narrated Anas Ibn Maalik [may Allaah be pleased with him] that the Prophet [peace and blessings of Allaah be upon him] said, “Do you know what Al-Ad’hu is [i.e. calumny]?” They said, “Allaah and His Messenger know best”. He said, “Transmitting speech from some people to another people in order to destroy their (mutual relationships)”.
Al-Allaamah Zayd Bin Haadi Al-Mad’khali [may Allaah have mercy upon him] said, “The subject matter of this hadeeth is about the dangerous (consequences) of tale-carrying in this Dunyaa and in the Aaakhirah. Indeed, the Prophet [peace and blessings of Allaah be upon him] called it Ad’hu, and the meaning of Ad’hu is to transmit speech from some people to another people in order to corrupt their relationships. And in the hadeeth of Ibn Mas’ud [may allaah be pleased with him], it is explained to mean tale-carrying, and that is to transmit the statement of one person to another person, or from a group of people to another group, or from one country to another one, in order to cause corruption.
This is one of the major sins due to its evil and the punishment (associated with it) in this life and the next. In this worldly life, it may lead to murder, chaos and other similar affairs – events that are in opposition to rectification. And due to this, the scholars say that the tale carrier- the one who transmits speech from one person to another person, or from a group of people to another group, or from one country to another, in order to sow the seeds of corruption- causes more harm than a magician. This is because a magician might only harm one person, but as for the tale-carrier, he might harm many individuals and the trial is prolonged.
Therefore, it is forbidden for a Muslim to transmit speech to cause corruption between those upon brotherhood and those who aid one another upon piety. And even if nothing like this [i.e. fighting, chaos, killing etc] occurs, it is still not permissible to corrupt the relationship between the people by way of lies- sowing the seeds of enmity and hatred between them. The Messenger of Allaah went past two graves and then said, “Both of them (i.e. the two people in these graves) are being punished, and they are not being punished due to (committing the greatest of the major sins), but indeed they are great sins. One of them used not to protect himself from being soiled with his urine, and the other one used to go about with tale-carrying”.
Therefore, what the opposite of this hadeeth (necessitates is that) it is obligatory to bring about reconciliation between the people due to the statement of Allaah[The Exalted]:
[لَّا خَيۡرَ فِى ڪَثِيرٍ۬ مِّن نَّجۡوَٮٰهُمۡ إِلَّا مَنۡ أَمَرَ بِصَدَقَةٍ أَوۡ مَعۡرُوفٍ أَوۡ إِصۡلَـٰحِۭ بَيۡنَ ٱلنَّاسِۚ – There is no good in most of their secret talks save (in) him who orders Sadaqah (charity in Allah’s Cause), or Ma’ruf (Islamic Monotheism and all the good and righteous deeds which Allah has ordained), or conciliation between mankind. [Surah An-Nisaa. Aayah 114]
However, there is an exception in this affair when it is carried out for the purpose of giving some sincere advice whose benefit cannot be reached nor can harm be repelled except by way of such speech. For example, you hear a person saying that he is lying in wait against your Muslim brother and wishes to kill him, take his wealth or violate his honour, or the like thereof, (whose evil consequences) you have clarified (for this perpetrator in order to stop him), but he refuses to accept your advice. Therefore, you go to the person who is unaware and informed him about it, so that he can take precautions. Therefore, speech based on this type of intention and goal is considered to be sincere advice and it is not tantamount to causing corruption, for indeed you are either going to repel harm or bring about a benefit which one cannot do without (except by way of this transmission). And Allaah knows best. (3)
[Ref 1: An Excerpt from ‘Atta-thab’but Fil-Akhbaar’ pages 34-36. slightly paraphrased]
[Ref 2: https://www.binbaz.org.sa/noor/2527
[Ref 3: At-ta’leeqaat Al-Maleehah Alaa Silsilatil Ahaadeeth As-Saheehah’ 1/27-28]