مشكوة المصابيح Mishkat al-Masabih كتاب القصاص The Book of Retaliation
(لَا يَجُوزُ قَتْلُ مَنْ قَرَأَ الْكَلِمَةَ الطَّيِّبَةَ)

(It is not permissible to kill someone who recites the testimony of faith)

1 hadith
Hadith 3450
وَعَنْ أُسَامَةَ بْنِ زَيْدٍ قَالَ: بَعَثَنَا رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِلَى أُنَاسٍ مِنْ جُهَيْنَةَ فَأَتَيْتُ عَلَى رَجُلٍ مِنْهُمْ فَذَهَبْتُ أَطْعَنُهُ فَقَالَ: لَا إِلَهَ إِلَّا اللَّهُ فَطَعَنْتُهُ فَقَتَلْتُهُ فَجِئْتُ إِلَى النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَأَخْبَرْتُهُ فَقَالَ: «أقَتلتَه وقدْ شَهِدَ أَنْ لَا إِلَهَ إِلَّا اللَّهُ؟» قُلْتُ: يَا رَسُولَ اللَّهِ إِنَّمَا فَعَلَ ذَلِكَ تَعَوُّذًا قَالَ: «فهَلاَّ شقَقتَ عَن قلبه؟»
Usama b. Zaid said:God’s Messenger sent us to some people of Juhaina, and I attacked one of them and was about to spear him when he said, “There is no god but God.” I then speared him and killed him, after which I went and told the Prophet. He said, “Did you kill him when he had testified that there is no god but God?” I replied, “Messenger of God, he did that only as a means to escape death.” He asked, “Why did you not split his heart?” Bukhari and Muslim.
Hadith Reference Mishkat al-Masabih / The Book of Retaliation / Hadith: 3450
Hadith Grading الألبانی: مُتَّفَقٌ عَلَيْهِ  |  زبیر علی زئی: متفق عليه
Hadith Takhrij ´تحقيق و تخريج: محدث العصر حافظ زبير على زئي رحمه الله` «متفق عليه، رواه البخاري (6872) و مسلم (96/158)»