صحيح البخاري

Narrated 'Ubaidullah bin `Adi bin Al-Khiyar:

That Al-Miqdad bin `Amr Al-Kindi, who was an ally of Bani Zuhra and one of those who fought the battle of Badr together with Allah's Messenger (ﷺ) told him that he said to Allah's Messenger, "Suppose I met one of the infidels and we fought, and he struck one of my hands with his sword and cut it off and then took refuge in a tree and said, "I surrender to Allah (i.e. I have become a Muslim),' could I kill him, O Allah's Messenger, after he had said this?" Allah's Messenger (ﷺ) said, "You should not kill him." Al- Miqdad said, "O Allah's Messenger! But he had cut off one of my two hands, and then he had uttered those words?" Allah's Messenger (ﷺ) replied, "You should not kill him, for if you kill him, he would be in your position where you had been before killing him, and you would be in his position where he had been before uttering those words."