It was narrated from 'Abdullah, who is Ibn Mas`ud, that the Messenger of Allah ﷺ said:
“It is not lawful to shed the blood of a Muslim who bears witness that none has the right to be worshiped but Allah (Subhanahu-wa-Taala), and that I am the Messenger of Allah ﷺ, except in one of three cases: a soul for a soul; a married person who commits adultery, and one who leaves his religion and splits from the Jama`ah.”

حَدَّثَنَا عَلِيُّ بْنُ مُحَمَّدٍ، وَأَبُو بَكْرِ بْنُ خَلاَّدٍ الْبَاهِلِيُّ قَالاَ حَدَّثَنَا وَكِيعٌ، عَنِ الأَعْمَشِ، عَنْ عَبْدِ اللَّهِ بْنِ مُرَّةَ، عَنْ مَسْرُوقٍ، عَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ، قَالَ قَالَ رَسُولُ اللَّهِ ﷺ " لاَ يَحِلُّ دَمُ امْرِئٍ مُسْلِمٍ يَشْهَدُ أَنْ لاَ إِلَهَ إِلاَّ اللَّهُ وَأَنِّي رَسُولُ اللَّهِ إِلاَّ أَحَدُ ثَلاَثَةِ نَفَرٍ النَّفْسُ بِالنَّفْسِ وَالثَّيِّبُ الزَّانِي وَالتَّارِكُ لِدِينِهِ الْمُفَارِقُ لِلْجَمَاعَةِ " .