حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ حَدَّثَنَا شُعْبَةُ عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ سَمِعْتُ ابْنَ عُمَرَ يُحَدِّثُ عَنْ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَنَّهُ قَالَ إِذَا قَالَ الرَّجُلُ لِلرَّجُلِ يَا كَافِرُ فَقَدْ بَاءَ بِهِ أَحَدُهُمَا إِنْ كَانَ كَمَا قَالَ وَإِلَّا رَجَعَتْ عَلَى الْآخَرِ
مسند امام احمد بن حنبل · Hadith 5035
It was narrated from 'Abdullah ibn Dinar: I heard Ibn 'Umar narrating from the Prophet (PBUH) that he said: "If one man says to another, 'O kaafir,’ it will apply to one of them. Either it is as he said, otherwise it will come back to him."
Translated by Dr. Muhammad Muhsin Khan · Reviewed by Islamic University of Madinah · Published March 2020