Muharamat - Prohibitions That Are Taken Too Lightly. Islamic book

Slander

Some people go about repeating the words of others to cause trouble between people; this is one of the greatest causes of broken relations and stirring up feelings of hatred among people. Allaah condemned the one who does this (interpretation of the meaning): "And obey not everyone who swears much, - and is considered worthless, a slanderer, going about with calumnies." [al-Qalam 68:10-11]

Hudhayfah reported that the Prophet (peace and blessings of Allaah be upon him) said: "No eavesdropper will enter Paradise." (Reported by al-Bukhaari, see al-Fath, 10/472; "eavesdropper" here refers to a person who eavesdrops on others without their knowing, then goes and tells others what he has heard)

Ibn 'Abbaas said: "The Prophet (peace and blessings of Allaah be upon him) passed by one of the gardens of Madeenah, and heard the sound of two people being punished in their graves. The Prophet (peace and blessings of Allaah be upon him) said: "They are being punished, but they are not being punished for any major sin; one of them used never to clean himself properly after urinating, and the other used to spread malicious slander . . ." (Reported by al-Bukhaari; see Fath al-Baari, 1/317).

One of the worst forms of this sin is to cause trouble between a husband and wife, or vice versa, or to tell one's boss what other employees are saying, in order to create trouble. All of this is haraam..