Prohibition of Calumny

Ibn 'Abbas (May Allah be pleased with them) said:
The Messenger of Allah ﷺ passed by two graves and said, "Both of them (the persons in these graves) are being tortured, and they are not being tortured for a cardinal sin. But indeed they are great sins. One of them used not to save himself from being soiled with his urine, and the other one used to go about with calumnies (among the people to rouse hostilities, e.g., one goes to a person and tells him that so-and-so says about him such and such evil things)."

[Al-Bukhari and Muslim].

وعن ابن عباس رضي الله عنهما أن رسول الله ﷺ مر بقبرين فقال: “إنهما يعذابان ، وما يعذبان في كبير! بلى إنه كبير: أما أحدهما ، فكان يمشي بالنميمة، وأما الآخر فكان لا يستتر من بوله ((متفق عليه وهذا لفظ إحدى روايات البخاري)). قال العلماء: معنى "وما يعذبان في كبير" أي كبير في زعمهما وقيل: كبير تركه عليهما.

Ibn Mas'ud (May Allah be pleased with him) said:
The Prophet ﷺ said, "Shall I tell you what 'Al-'Adhu' (falsehood and slandering) is? It is calumny which is committed among the people."

[Muslim].

وعن ابن مسعود رضي الله عنه أن النبي ﷺ قال: “ ألا أنبئكم ما العِضَه؟ هي النميمة، القالة بين الناس" ((رواه مسلم)).