Sahih al-Bukhari 6862
Sahih al-Bukhari · Book 87: Blood Money (Ad-Diyat) · “… And whoever kills a believer intentionally, his recompense is Hell …”
Narrated Ibn `Umar:
حَدَّثَنَا عَلِيٌّ ، حَدَّثَنَا إِسْحَاقُ بْنُ سَعِيدِ بْنِ عَمْرِو بْنِ سَعِيدِ بْنِ الْعَاصِ ، عَنْ أَبِيهِ ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما ـ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لَنْ يَزَالَ الْمُؤْمِنُ فِي فُسْحَةٍ مِنْ دِينِهِ، مَا لَمْ يُصِبْ دَمًا حَرَامًا " .
Allah's Messenger (ﷺ) said, "A faithful believer remains at liberty regarding his religion unless he kills somebody unlawfully."