From `Abdul-`Azeez ibn `Abdullaah ibn Baaz to those who see it of my Muslim brothers, may Allaah grant me and them success in fulfilling what pleases Him, and keep us away from disobeying Him, Aaameeen!
al-salaamu `Alaykum wa rahmatullaah wa barakaatuh (May Allaah’s Peace, Mercy, and Blessings be upon you). To proceed:
I advise every Muslim to have Taqwaa (fear or wariness of offending Allaah) in all circumstances and guard his tongue from saying anything other than that which is useful, because Mubaah (permissible) talk may lead to what is Haraam (prohibited) or Makrooh (disliked), and this is common among people. Allaah (Exalted be He) says: Not a word does he (or she) utter but there is a watcher by him ready (to record it). Allaah (Exalted be He) also says: And follow not (O man i.e., say not, or do not or witness not) that of which you have no knowledge. Verily! The hearing, and the sight, and the heart, of each of those one will be questioned (by Allaah). The Prophet (peace be upon him) also said in the Hadeeth agreed upon by Al-Bukhaaree and Muslim and narrated by Aboo Hurayrah (may Allaah be pleased with him): Anyone who believes in Allaah and the Last Day should either utter good words or stay silent.
There are bad things that talking may lead people to commit and should be warned against, for they constitute major sins, which would bring down Allaah’s Anger and His Punishment. These things have become commonly widespread in some communities and they include the following:
1- Backbiting: That is talking about your brother or sister in a way that they would dislike, if they heard about it, whether by talking about their shape, family, character, actions, sayings or about their religion or life, or even talking ill about their clothes,home or car. Aboo Hurayrah (may Allah be pleased with him) reported that the Prophet (peace be upon him) said: ‘Do you know what backbiting is?’ His companions replied, ‘Allaah and His Messenger know best.’ He (peace be upon him) said, ‘It is to say something about your brother that he would dislike.’ Someone asked, ‘But what if what I say about my brother is true?’ He (peace be upon him) said, ‘If what you say about him is true, then you have backbitten him, but if it is not true, then you have slandered him.’ (Related by Muslim)… read more here.