Narrated `Abdullah: Allah's Apostle said, "Abusing a Muslim is Fusuq (i.e., an evil-doing), and killing him is Kufr (disbelief).

Narrated Abu Dhar: That he heard the Prophet saying, "If somebody accuses another of Fusuq (by calling him 'Fasiq' i.e. a wicked person) or accuses him of Kufr, such an accusation will revert to him (i.e. the accuser) if his companion (the accused) is innocent."

Narrated Anas: Allah's Apostle was neither a Fahish (one who had a bad tongue) nor a Sabbaba (one who abuses others) and he used to say while admonishing somebody, "What is wrong with him? May dust be on his forehead!"

Narrated Thabit bin Ad-Dahhak: (who was one of the companions who gave the pledge of allegiance to the Prophet underneath the tree (Al-Hudaibiya)) Allah's Apostle said, "Whoever swears by a religion other than Islam (i.e. if somebody swears by saying that he is a non-Muslim e.g., a Jew or a Christian, etc.) in case he is telling a lie, he is really so if his oath is false, and a person is not bound to fulfill a vow about a thing which he does not possess. And if somebody commits suicide with anything in this world, he will be tortured with that very thing on the Day of Resurrection; And if somebody curses a believer, then his sin will be as if he murdered him; And whoever accuses a believer of Kufr (disbelief), then it is as if he killed him."

Narrated Sulaiman bin Surad: A man from the companions of the Prophet said, "Two men abused each other in front of the Prophet and one of them became angry and his anger became so intense that his face became swollen and changed. The Prophet said, "I know a word the saying of which will cause him to relax if he does say it." Then a man went to him and informed him of the statement of the Prophet and said, "Seek refuge with Allah from Satan." On that, angry man said, 'Do you find anything wrong with me? Am I insane? Go away!"

Narrated 'Ubada bin As-Samit: Allah's Apostle went out to inform the people about the (date of the Night of decree (Al-Qadr). There happened a quarrel between two Muslim men. The Prophet said, "I came out to inform you about the Night of Al-Qadr, but as so-and-so and so-and-so quarrelled, so the news about it had been taken away; and may be it was better for you. So look for it in the ninth, the seventh, or the fifth (of the last ten days of Ramadan).

Narrated Ma'rur: I saw Abu Dhar wearing a Burd (garment) and his slave too was wearing a Burd, so I said (to Abu Dhar), "If you take this (Burda of your slave) and wear it (along with yours), you will have a nice suit (costume) and you may give him another garment." Abu Dhar said, "There was a quarrel between me and another man whose mother was a non-Arab and I called her bad names. The man mentioned (complained about) me to the Prophet. The Prophet said, "Did you abuse so-and-so?" I said, "Yes" He said, "Did you call his mother bad names?" I said, "Yes". He said, "You still have the traits of (the Pre-lslamic period of) ignorance." I said. "(Do I still have ignorance) even now in my old age?" He said, "Yes, they (slaves or servants) are your brothers, and Allah has put them under your command. So the one under whose hand Allah has put his brother, should feed him of what he eats, and give him dresses of what he wears, and should not ask him to do a thing beyond his capacity. And if at all he asks him to do a hard task, he should help him therein."