كتاب القسامة
Read the English translation first, with the original Arabic directly underneath.
It was narrated from 'Abdullah that the Messenger of Allah said:
"It is not permissible to shed the blood of a Muslim except in one of three cases: A soul for a soul, a adulterer who has been married, and one who separates leaving his religion."
لاَ يَحِلُّ دَمُ امْرِئٍ مُسْلِمٍ إِلاَّ بِإِحْدَى ثَلاَثٍ النَّفْسُ بِالنَّفْسِ وَالثَّيِّبُ الزَّانِي وَالتَّارِكُ دِينَهُ الْمُفَارِقُ