وعن ابن مسعود رضي الله عنه قال‏:‏ قال رسول الله صلى الله عليه وسلم ‏:‏ ‏"‏سباب المسلم فسوق، وقتاله كفر‏"‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏‏.‏

Ibn Mas'ud (May Allah be pleased with him) reported

The Messenger of Allah (ﷺ) said, "Reviling a Muslim is Fusuq (disobedience of Allah) and killing him is (tantamount to) disbelief."[Al-Bukhari and Muslim].