(41) باب تَحْرِيمِ قَتْلِ الْكَافِرِ بَعْدَ أَنْ قَالَ لاَ إِلَهَ إِلاَّ اللَّهُ
It is narrated on the authority of Usama b. Zaid:
The Messenger of Allah may peace be upon him) sent us to Huraqat, a tribe of Juhaina. We attacked that tribe early in the morning and defeated them and I and a man from the Ansar caught hold of a person (of the defeated tribe). When we overcame him, he said: There is no god but Allah. At that moment the Ansari spared him, but I attacked him with my spear and killed him. The news had already reached the Apostle (peace be upon him), so when we came back he (the Apostle) said to me: Usama, did you kill him after he had made the profession: There is no god but Allah? I said. Messenger of Allah, he did it only as a shelter. The Prophet observed: Did you kill him after he had made the profession that there is no god but Allah? He (the Holy Prophet) went on repeating this to me till I wished I had not embraced Islam before that day.
Reference: Sahih Muslim 96 b
In-book reference: Book 1, Hadith 184
USC-MSA web (English) reference(deprecated numbering scheme): Book 1, Hadith 177