Narrated Al-Miqdad bin 'Amr Al-Kindi:

An ally of Bani Zuhra who took part in the battle of Badr with the Prophet, that he said, "O Allah's Apostle! If I meet an unbeliever and we have a fight, and he strikes my hand with the sword and cuts it off, and then takes refuge from me under a tree, and says, 'I have surrendered to Allah (i.e. embraced Islam),' may I kill him after he has said so?" Allah's Apostle ﷺ said, "Do not kill him." Al-Miqdad said, "But O Allah's Apostle! He had chopped off one of my hands and he said that after he had cut it off. May I kill him?" The Prophet ﷺ said. "Do not kill him for if you kill him, he would be in the position in which you had been before you kill him, and you would be in the position in which he was before he said the sentence." The Prophet also said to Al-Miqdad, "If a faithful believer conceals his faith (Islam) from the disbelievers, and then when he declares his Islam, you kill him, (you will be sinful). Remember that you were also concealing your faith (Islam) at Mecca before."

حَدَّثَنَا عَبْدَانُ، حَدَّثَنَا عَبْدُ اللَّهِ، حَدَّثَنَا يُونُسُ، عَنِ الزُّهْرِيِّ، حَدَّثَنَا عَطَاءُ بْنُ يَزِيدَ، أَنَّ عُبَيْدَ اللَّهِ بْنَ عَدِيٍّ، حَدَّثَهُ أَنَّ الْمِقْدَادَ بْنَ عَمْرٍو الْكِنْدِيَّ حَلِيفَ بَنِي زُهْرَةَ حَدَّثَهُ وَكَانَ، شَهِدَ بَدْرًا مَعَ النَّبِيِّ ﷺ أَنَّهُ قَالَ يَا رَسُولَ اللَّهِ إِنْ لَقِيتُ كَافِرًا فَاقْتَتَلْنَا، فَضَرَبَ يَدِي بِالسَّيْفِ فَقَطَعَهَا، ثُمَّ لاَذَ بِشَجَرَةٍ وَقَالَ أَسْلَمْتُ لِلَّهِ. آقْتُلُهُ بَعْدَ أَنْ قَالَهَا قَالَ رَسُولُ اللَّهِ ﷺ " لاَ تَقْتُلْهُ ". قَالَ يَا رَسُولَ اللَّهِ فَإِنَّهُ طَرَحَ إِحْدَى يَدَىَّ، ثُمَّ قَالَ بَعْدَ مَا قَطَعَهَا، آقْتُلُهُ قَالَ " لاَ تَقْتُلْهُ، فَإِنْ قَتَلْتَهُ فَإِنَّهُ بِمَنْزِلَتِكَ قَبْلَ أَنْ تَقْتُلَهُ، وَأَنْتَ بِمَنْزِلَتِهِ قَبْلَ أَنْ يَقُولَ كَلِمَتَهُ الَّتِي قَالَ ". وَقَالَ حَبِيبُ بْنُ أَبِي عَمْرَةَ عَنْ سَعِيدٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَالَ النَّبِيُّ ﷺ لِلْمِقْدَادِ " إِذَا كَانَ رَجُلٌ مُؤْمِنٌ يُخْفِي إِيمَانَهُ مَعَ قَوْمٍ كُفَّارٍ، فَأَظْهَرَ إِيمَانَهُ، فَقَتَلْتَهُ، فَكَذَلِكَ كُنْتَ أَنْتَ تُخْفِي إِيمَانَكَ بِمَكَّةَ مِنْ قَبْلُ ".