Someone says calls his brother an unbeliever

'Abdullah ibn 'Umar reported that the Messenger of Allah, (ﷺ), said, "If a man says to his brother, 'You are an unbeliever,' it is true for one or the other of them."

حَدَّثَنَا إِسْمَاعِيلُ، قَالَ‏:‏ حَدَّثَنَا مَالِكٌ، عَنْ عَبْدِ اللهِ بْنِ دِينَارٍ، عَنْ عَبْدِ اللهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللهِ صلى الله عليه وسلم قَالَ‏:‏ أَيُّمَا رَجُلٌ قَالَ لأَخِيهِ‏:‏ كَافِرٌ، فَقَدْ بَاءَ بِهَا أَحَدُهُمَا‏.‏

'Abdullah ibn 'Umar reported that the Messenger of Allah, (ﷺ), said, "When someone says to another, 'Unbeliever!' then one of them is an unbeliever. If the one to whom he says it is an unbeliever, he has spoke the truth. If that is not the case, then the one who said it has brought down disbelief on himself."

حَدَّثَنَا سَعِيدُ بْنُ دَاوُدَ، قَالَ‏:‏ حَدَّثَنَا مَالِكٌ، أَنَّ نَافِعًا حَدَّثَهُ، أَنَّ عَبْدَ اللهِ بْنَ عُمَرَ أَخْبَرَهُ، أَنَّ رَسُولَ اللهِ صلى الله عليه وسلم قَالَ‏:‏ إِذَا قَالَ لِلْآخَرِ‏:‏ كَافِرٌ، فَقَدْ كَفَرَ أَحَدُهُمَا، إِنْ كَانَ الَّذِي قَالَ لَهُ كَافِرًا فَقَدْ صَدَقَ، وَإِنْ لَمْ يَكُنْ كَمَا قَالَ لَهُ فَقَدْ بَاءَ الَّذِي قَالَ لَهُ بِالْكُفْرِ‏.‏