Prohibition of Reviling a Muslim without any cause

Imam Al-Nawawi’s Riyad-us-Saliheen
Chapter 266
Prohibition of Reviling a Muslim without any cause

Allah, the Exalted, says:

And those who annoy believing men and women undeservedly, bear on themselves the crime of slander and plain sin.” (33:58)

1559. Ibn Mas`ud (May Allah be pleased with him) reported: The Messenger of Allah (sallallaahu ’alayhi wa sallam) said, “Reviling a Muslim is Fusuq (disobedience of Allah) and killing him is (tantamount to) disbelief.”
[Al-Bukhari and Muslim].

1560. Abu Dharr (May Allah be pleased with him) reported: I heard the Messenger of Allah (sallallaahu ’alayhi wa sallam) saying, “When any Muslim accuses another Muslim of sin or of disbelief, the reproach rebounds upon the one who utters it, if the other person is not deserving of it.”
[Al-Bukhari].

1561. Abu Hurairah (May Allah be pleased with him) said: The Messenger of Allah (sallallaahu ’alayhi wa sallam) said, “When two persons indulge in abusing each other, the beginner will be the sinner so long as the oppressed does not transgress the limits.”
[Muslim].

1562. Abu Hurairah (May Allah be pleased with him) said: A drunkard was brought to the Prophet (sallallaahu ’alayhi wa sallam). He said, “Give him a beating.” Then some beat him with their hands, some with their shoes, and some with (a folded) piece of cloth. When he left, someone said to him: “May Allah disgrace you!” The Prophet (sallallaahu ’alayhi wa sallam) said, “Do not help Satan overcome him by uttering such words.”
[Al-Bukhari].

1563. Abu Hurairah (May Allah be pleased with him) said: I heard the Messenger of Allah (sallallaahu ’alayhi wa sallam) saying, “He who accuses his slave of Zina will receive the punishment (Hadd) of slander on the Day of Resurrection, unless the accusation of Zina was true.”
[Al-Bukhari and Muslim].