Abusive behavior is evil and murder is disbelief

The Prophet ﷺ said, "Abusing a Muslim is fusūq (evil doings) and killing him is kufr (disbelief)."  

أَنَّ النَّبِيَّ ﷺ قَالَ: «سِبَابُ الْمُسْلِمِ فُسُوقٌ وَقِتَالُهُ كُفْرٌ۔»  

Messenger of Allah ﷺ said, "Abusing a Muslim is Fusuq (i.e., an evil-doing), and killing him is Kufr (disbelief).  

قَالَ رَسُولُ اللَّهِ ﷺ سِبَابُ الْمُسْلِمِ فُسُوقٌ وَقِتَالُهُ كُفْرٌ  

The Prophet, said, "Abusing a Muslim is Fusuq (evil doing) and killing him is Kufr (disbelief).  

قَالَ النَّبِيُّ ﷺ سِبَابُ الْمُسْلِمِ فُسُوقٌ وَقِتَالُهُ كُفْرٌ  

That he heard the Prophet ﷺ saying, "If somebody accuses another of Fusuq (by calling him 'Fasiq' i.e. a wicked person) or accuses him of Kufr, such an accusation will revert to him (i.e. the accuser) if his companion (the accused) is innocent."  

أَنَّهُ سَمِعَ النَّبِيَّ ﷺ يَقُولُ لاَ يَرْمِي رَجُلٌ رَجُلاً بِالْفُسُوقِ وَلاَ يَرْمِيهِ بِالْكُفْرِ إِلاَّ ارْتَدَّتْ عَلَيْهِ إِنْ لَمْ يَكُنْ صَاحِبُهُ كَذَلِكَ  

When two persons indulge in hurling (abuses) upon one another, it would be the first one who would be the sinner so long as the oppressed does not transgress the limits.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ الْمُسْتَبَّانِ مَا قَالاَ فَعَلَى الْبَادِئِ مَا لَمْ يَعْتَدِ الْمَظْلُومُ  

Abu Huraira said, "A man who drank wine was brought to the Prophet. The Prophet ﷺ said, 'Beat him!" Abu Huraira added, "So some of us beat him with our hands, and some with their shoes, and some with their garments (by twisting it) like a lash, and then when we finished, someone said to him, 'May Allah disgrace you!' On that the Prophet ﷺ said, 'Do not say so, for you are helping Satan to overpower him.' "  

عَنْ أَبِي هُرَيْرَةَ ؓ أُتِيَ النَّبِيُّ ﷺ بِرَجُلٍ قَدْ شَرِبَ قَالَ اضْرِبُوهُ قَالَ أَبُو هُرَيْرَةَ فَمِنَّا الضَّارِبُ بِيَدِهِ وَالضَّارِبُ بِنَعْلِهِ وَالضَّارِبُ بِثَوْبِهِ فَلَمَّا انْصَرَفَ قَالَ بَعْضُ الْقَوْمِ أَخْزَاكَ اللَّهُ قَالَ لاَ تَقُولُوا هَكَذَا لاَ تُعِينُوا عَلَيْهِ الشَّيْطَانَ  

He who accused his slave of adultery, punishment would be imposed upon him on the Day of Resurrection, except in case the accusation was as he had said.  

أَبُو الْقَاسِمِ ﷺ مَنْ قَذَفَ مَمْلُوكَهُ بِالزِّنَا يُقَامُ عَلَيْهِ الْحَدُّ يَوْمَ الْقِيَامَةِ إِلاَّ أَنْ يَكُونَ كَمَا قَالَ  

"If somebody slanders his slave (by accusing him of committing illegal sexual intercourse) and the slave is innocent from what he says, Allah will impose the punishment upon him on the Day of Resurrection, unless it is as he said about him."  

أَبُو الْقَاسِمِ ﷺ نَبِيُّ التَّوْبَةِ مَنْ قَذَفَ مَمْلُوكَهُ بَرِيئًا مِمَّا قَالَ لَهُ أَقَامَ عَلَيْهِ الْحَدَّ يَوْمَ الْقِيَامَةِ إِلاَّ أَنْ يَكُونَ كَمَا قَالَ