He replied, “Messenger of Allah, he severed one of my hands and only after that did he say those words!” The Prophet said, “Do not kill him; for if you do, he will be in the same position you were in before you killed him, whereas you will be in the position he was in before he uttered the words he uttered.” Agreed upon.

The meaning of “he will be in your position” is that his blood is protected and he is to be judged a Muslim; and “you will be in his position” means that your blood would be subject to lawful retaliation by his heirs. It does not mean that you would share his disbelief. Allah knows best.

4/393 – Usamah ibn Zayd (may Allah be pleased with him) said: The Messenger of Allah ﷺ sent us against al-Hurqa of Juhaynah. We surprised the people at their watering places, and I, together with a man from the Ansar, chased one of them. When we caught up with him he exclaimed, “There is no god but Allah.” The Ansari held back, but I struck him with my spear and killed him. When we reached Madinah and the Prophet ﷺ heard of it, he said to me, “Usamah, did you kill him after he said, ‘There is no god but Allah’?” He kept repeating that question to me until I wished I had not embraced Islam before that day. Agreed upon.

In another version: The Messenger of Allah ﷺ said, “He said, ‘There is no god but Allah,’ and you still killed him?!” I replied, “Messenger of Allah, he only said it out of fear of the weapon.” He said, “Did you split open his heart so that you could know whether he said it sincerely or not?!” He kept repeating it until I wished I had embraced Islam on that very day.

“Al-Hurqa,” with a ḍamma on the ḥāʾ and a fatḥa on the rāʾ, is a sub-clan of the well-known tribe of Juhaynah. The phrase “seeking refuge” means he uttered it for protection from being killed, not out of genuine belief.