Hadith on Takfir: Accusations of unbelief can backfire on accusers

Abu Huraira reported: The Messenger of Allah, peace and blessings be upon him, said, “When a man accuses his brother of being an unbeliever, then it will be turned against at least one of them.

Source: Ṣaḥīḥ al-Bukhārī 6103

Grade: Sahih (authentic) according to Al-Bukhari

عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ إِذَا قَالَ الرَّجُلُ لِأَخِيهِ يَا كَافِرُ فَقَدْ بَاءَ بِهِ أَحَدُهُمَا

6103 صحيح البخاري كتاب الأدب باب من كفر أخاه بغير تأويل فهو كما قال