Sunnah.com reference : Book 9, Hadith 2English translation : Book 9, Hadith 1200Arabic reference : Book 9, Hadith 1170
'A’ishah (RAA) narrated that Allah’s Messenger (ﷺ) said:
“The blood of a Muslim is not to be shed except for three reasons: a married man who committed adultery, a man who kills another Muslim intentionally for which he must be killed (in Qisas or retaliation), and a man who abandons Islam and fights against Allah and His Messenger, in which case he should be either killed, crucified, or exiled.” Related by Abu Dawud and An-Nasa’i. Al-Hakim graded it as Sahih.
وَعَنْ عَائِشَةَ رَضِيَ اَللَّهُ عَنْهَا, عَنْ رَسُولِ اَللَّهِ ‏- صلى الله عليه وسلم ‏-قَالَ: { لَا يَحِلُّ قَتْلُ مُسْلِمٍ إِلَّا فِي إِحْدَى ثَلَاثِ خِصَالٍ: زَانٍ مُحْصَنٌ فَيُرْجَمُ, وَرَجُلٌ يَقْتُلُ مُسْلِمًا مُتَعَمِّدًا فَيُقْتَلُ, وَرَجُلٌ يَخْرُجُ مِنْ اَلْإِسْلَامِ فَيُحَارِبُ اَللَّهَ وَرَسُولَهُ, فَيُقْتَلُ, أَوْ يُصْلَبُ, أَوْ يُنْفَى مِنْ اَلْأَرْضِ .‏ }  رَوَاهُ أَبُو دَاوُدَ, وَالنَّسَائِيُّ, وَصَحَّحَهُ اَلْحَاكِمُ  1‏ .‏‏1 ‏- صحيح.‏ رواه أبو داود (4353)‏، والنسائي (7/91)‏، والحاكم (4 /367)‏.‏