مُوَطَّأُ مَالِكٍ
Muwatta Malik 1814
Speech
حَدَّثَنِي مَالِكٌ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ مَنْ قَالَ لأَخِيهِ يَا كَافِرُ . فَقَدْ بَاءَ بِهَا أَحَدُهُمَا .
Malik related to me from Abdullah ibn Dinar from Abdullah ibn Umar that the Messenger of Allah, (ﷺ), said, "If a man says to his muslim brother, 'O kafir!' it is true about one of them."
Arabic/English book reference: Book 56, Hadith 1