The Messenger of Allah ﷺ sent us on an expedition to al-Huraqah. We attacked the people at dawn and routed them. I and a man from the Ansar caught up with one of their men, and when we overpowered him, he said, "There is no god but Allah."The Ansari held back from him, but I struck him with my spear and killed him. When we returned, news of this reached the Prophet ﷺ, and he said, "Usama, did you kill him after he said, 'There is no god but Allah'?"I said, "He only said it to seek protection."He kept repeating it to me until I wished I had not become a Muslim before that day.
بعثنا رسول الله ﷺ إلى الحرقة، فصبحنا القوم فهزمناهم، ولحقت أنا ورجل من الأنصار رجلا منهم فلما غشيناه قال: لا إله إلا الله. فكف عنه الأنصاري، فطعنته برمحي حتى قتلته، فلما قدمنا بلغ ذلك النبي ﷺ فقال: يا أسامة، أقتلته بعدما قال: لا إله إلا الله؟ قلت: كان متعوذا! فما زال يكررها حتى تمنيت أني لم أكن أسلمت قبل ذلك اليوم.
Bukhari reported it in the Book of Military Expeditions (4269), and Muslim in the Book of Faith (96, 159), both through the route of Hushaym, who said, our informant was Husayn, who said, our narrator was Abu Dhubyan, who said, I heard Usama bin Zayd bin Haritha narrating, and he said (as previously mentioned), and their wording is identical.Muslim also reported it through another route, from Amash, from Abu Dhubyan, from Usama bin Zayd, who said, The Messenger of Allah ﷺ sent us on a raiding expedition, and we attacked the Huraqat of Juhayna at dawn. I caught up with a man and he said, "There is no god but Allah," but I stabbed him anyway. This weighed on my conscience, so I mentioned it to the Prophet, and the Messenger of Allah ﷺ said, "Did he say, 'There is no god but Allah,' and you still killed him?"I said, "Messenger of Allah, he only said it out of fear of the weapon."He said, "Why didn't you cut open his heart so you could know whether he really said it or not?"He kept repeating this to me until I wished I had only become a Muslim on that very day.Saad then said, "By Allah, I will never kill a Muslim until the one with the belly kills him," meaning Usama.A man said, "Did Allah not say, "Fight them until there is no more fitnah, and religion belongs entirely to Allah" [Anfal 8:39]?"Saad replied, "We fought until there was no more fitnah, but you and your companions want to fight until there is fitnah."His statement, "the Huraqat," is like Arafat and Adhruat, a place in the lands of Juhayna.