حَدَّثَنَا عُثْمَانُ بْنُ أَبِي شَيْبَةَ حَدَّثَنَا جَرِيرٌ عَنْ فُضَيْلِ بْنِ غَزْوَانَ عَنْ نَافِعٍ عَنْ ابْنِ عُمَرَ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّی اللَّهُ عَلَيْهِ وَسَلَّمَ أَيُّمَا رَجُلٍ مُسْلِمٍ أَکْفَرَ رَجُلًا مُسْلِمًا فَإِنْ کَانَ کَافِرًا وَإِلَّا کَانَ هُوَ الْکَافِرُ
سنن ابودوٗد · Hadith 4687
Ibn Umar reported the Messenger of Allah ﷺ as saying: If any believing man calls another believing man an unbeliever, if he is actually an infidel, it is all right ; if not, he will become an infidel.
Translated by Dr. Muhammad Muhsin Khan · Reviewed by Islamic University of Madinah · Published March 2020