Narrator:Abdullah ibn Mas‘ūd
وعن ابن مسعود رضي الله عنه قال: قال رسول الله صلى الله عليه وسلم :
"سباب المسلم فسوق، وقتاله كفر"
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].
Reported by Al-Bukhari (No. 48, 6044, 7076), Muslim (No. 64a), At-Tirmidhi (No. 1983, 2635), An-Nasa’i (No. 4105, 4107, 4108, 4109, 4110, 4111, 4112), Ibn Majah (No. 69, 3939) and Ahmad (No. 3465, 3708, 3916, 4115). Cited in Riyad as-Salihin (No. 1559).