The Holy Prophet [s] said: "Affliction caused by the tongue is worse than (that caused by) the strike of the blade of a sword."

Bihar-ul-Anwar, vol. 71, p. 286

The Holy Prophet [s] said: "Among all things, the tongue deserves to be prisoned longer than anything else." (Because most of our sins are committed by it, such as backbiting, telling lies, defaming, mocking, insulting, etc.)

Bihar-uI-Anwar vol. 71, p. 277

Imam Amir-ul-Mu'mineen Ali [a] said: "Do contemplate before speaking so that you may guard yourself from (committing) errs."

Ghurar-uI-Hikam, p. 228

The Holy Prophet [s] said: "The destruction of man lies in three (things): his stomach, his lusts, and his tongue."

Waqayi'-ul-'Ayyam, p. 297

Imam Baqir, the fifth Imam, [a] said: "No one is safe from sins unless the one controls his/her tongue."

Bihar-ul-Anwar, vol. 78, p. 178

Backbiting and Faultfinding

The Holy Prophet [s] said: "Slander acts quicker against the faith of a Muslim believer than leprosy does against his body."

Usul-I-Kafi, vol. 2, p. 257

Imam Amir-ul-Mu'mineen Mi [a] said: "The listener to backbiting is the same as the backbiter."

Ghurar-ul-Hikam, p. 307

The Holy Prophet [s] said: "The abandoning of backbiting is more valuable to Allah, Almighty and Glorious, than the performance of ten thousand rak'at of recommended prayers."

Bihar-ul-Anwar, vol. 75, p. 261

'Abd-ul-Mu'min-il-Ansari said that once he himself arrived in the presence of Imam Abil-Hassan Musa ibn Ja'far [a] where Abdillah-il-Ja'fari had attended and Abdul-Mu'min smiled at him. Then he [a] inquired whether Abdul-Mu'min liked Abdillah Al-Ja'fari when he replied to the Imam [a] that he did not like him ('Abdillah) but on his account (the seventh Imam). Then Imam [a] said: "He is your brother, and a Muslim believer is the brother of another Muslim believer though their fathers are not the same. Hence, cursed is he who accuses his (Muslim) brother, cursed is he who deceives his (Muslim) brother, cursed is he who does not advise his (Muslim) brother, and cursed is he who slanders his (Muslim) brother."

Bihar-ul-Anwar, vol. 75, p. 262

Imam Amir-ul-Mu'mineen Ali [a] said: "The most vicious person is he who looks for other people's defects while he overlooks his own faults."

Tara'if-ul-Hikam, p. 176

Imam Kazim [a] said: "Cursed is the one who backbites against one's brother (fellow Muslim)."

Bihar-ul-Anwar, vol. 74, p. 232

Telling Lies

'Anas-ibn-Mlaik narrates from the Messenger of Allah [s] who said: "Accept six things from me, then I will accept (and guarantee) the entrance of Heaven for you:

1. When you speak, tell no lies.
2. When you promise, do not break it.
3. When you are trusted (by others), be honest.
4. Lower your eyes (from committing sin).
5. Guard your modesty.
6. Hold your hands and tongues."

Khisal-i-Saduq, p. 321

Imam Abi-Muhammad-al-'Askari, the eleventh Imam, [a] said: "Wickedness was put inside a house, and the key (of its door) was rendered to be lies."

Bihar-ul-Anwar, vol. 72, p. 263

Imam Sajjad [a] said: "Avoid telling lies irrespective of small or great, whether it is in earnest or joking, because when a person tells a lie in small (things), he dares to tell a lie in great things, too."

Tuhaful-Uqul, p. 201

Once Imam Amir-ul-Mu'mineen Ali [a] was asked about the distance between the truth and untruth and, while he [a] was showing the distance between his eye and ear with his four fingers in order to illustrate this distance as his answer, he said: "What your eyes see is 'truth' and what your ears hear is for the most part 'untruth'."

Bihar-ul-Anwar, vol. 75, p. 196

Imam Baqir [a] said: "Verily, Allah, the exalted, has put some locks on vices, the key of which He has put in wine, but the vice of lying is worse than wine."

AI-Kafi, vol. 2, p. 339

Imam Rida [a] said: "Be truthful and avoid telling lies."

Bihar-ul-Anwar, vol. 78, p. 347