Prohibition of Reviling a Muslim without any cause

Abu Dharr (May Allah be pleased with him) reported:
I heard the Messenger of Allah ﷺ 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].

وعن أبي ذر رضي الله عنه أنه سمع رسول الله ﷺ يقول: "لا يرمي رجل رجلا بالفسق أو الكفر، إلا ارتدت عليه، إن لم يكن صاحبه كذلك" ((رواه البخاري)).

Abu Hurairah (May Allah be pleased with him) said:
The Messenger of Allah ﷺ 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].

وعن أبي هريرة رضي الله عنه أن رسول الله ﷺ قال: "المتسابان ما قالا فعلى البادي منهما حتى يعتدي المظلوم" ((رواه مسلم)).

Abu Hurairah (May Allah be pleased with him) said:
A drunkard was brought to the Prophet ﷺ. 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 ﷺ said, "Do not help Satan overcome him by uttering such words."

[Al-Bukhari].

وعنه قال: أتي النبي ﷺ برجل قد شرب قال: "اضربوه" قال أبو هريرة: فمنا الضارب بيده، والضارب بنعله، والضارب بثوبه. فلما انصرف، قال بعض القوم: أخزاك الله، قال: "لا تقولوا هذا، لا تُعينوا عليه الشيطان" ((رواه البخاري)).

Abu Hurairah (May Allah be pleased with him) said:
I heard the Messenger of Allah ﷺ 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].

وعنه قال: سمعت رسول الله ﷺ يقول: "من قذف مملوكه بالزنا يقام عليه الحد يوم القيامة، إلا أن يكون كما قال" ((متفق عليه)).