The Messenger of Allah ﷺ sent us on an expedition to the Huraqah clan of Juhaynah. We attacked them at dawn and fought them. Among them was a man who, whenever our forces advanced, was the fiercest against us, and whenever they retreated, he was their protector.A man from the Ansar and I closed in on him. When we overpowered him, he said, "There is no god but Allah."The Ansari held back from him, but I killed him.When news of this reached the Prophet ﷺ, he said, "Usama, did you kill him after he said, 'There is no god but Allah'?"I said, "Messenger of Allah, he only said it seeking refuge from being killed."He kept repeating this to me until I wished I had not become a Muslim until that very day.
حدثنا هشيم بن بشير حدثنا حصين عن أبي ظبيان قال سمعت
بعثنا رسول الله ﷺ إلى الحرقة من جهينة قال فصبحناهم فقاتلناهم فكان منهم رجل إذا أقبل القوم كان من أشدهم علينا وإذا أدبروا كان حاميتهم قال فغشيته أنا ورجل من الأنصار قال فلما غشيناه قال لا إله إلا الله فكف عنه الأنصاري وقتلته فبلغ ذلك النبي ﷺ فقال يا أسامة أقتلته بعدما قال لا إله إلا الله قال قلت يا رسول الله إنما كان متعوذا من القتل فكررها علي حتى تمنيت أني لم أكن أسلمت إلا يومئذ
Its isnad is sahih. Husayn is Ibn Abdul-Rahman Sulami, who has recurred many times, and he is trustworthy, his hadith being found in the collections of the group. Abu Dhubyan is Husayn bin Jundab, one of the trustworthy senior successors, and his hadith is found in the collections of the group.The hadith was narrated by Bukhari, 9/4, in the chapter on blood-money, on the words of Allah, the Exalted, "and whoever saves it has saved all of mankind" [Maidah 5:32], and by Muslim, 1/97, no. 96m. It is a well-known hadith that has already been given earlier in many wordings.