وَما كانَ لِمُؤمِنٍ أَن يَقتُلَ مُؤمِنًا إِلّا خَطَأً ۚ وَمَن قَتَلَ مُؤمِنًا خَطَأً فَتَحريرُ رَقَبَةٍ مُؤمِنَةٍ وَدِيَةٌ مُسَلَّمَةٌ إِلىٰ أَهلِهِ إِلّا أَن يَصَّدَّقوا ۚ فَإِن كانَ مِن قَومٍ عَدُوٍّ لَكُم وَهُوَ مُؤمِنٌ فَتَحريرُ رَقَبَةٍ مُؤمِنَةٍ ۖ وَإِن كانَ مِن قَومٍ بَينَكُم وَبَينَهُم ميثاقٌ فَدِيَةٌ مُسَلَّمَةٌ إِلىٰ أَهلِهِ وَتَحريرُ رَقَبَةٍ مُؤمِنَةٍ ۖ فَمَن لَم يَجِد فَصِيامُ شَهرَينِ مُتَتابِعَينِ تَوبَةً مِنَ اللَّهِ ۗ وَكانَ اللَّهُ عَليمًا حَكيمًا

It’s not for a believer to kill a believer, except by mistake. Whoever kills a believer accidentally, the compensation is to free a believing captive and pay compensation to his family, unless they remit it as a charity. If he belonged to a people hostile to you, yet was a believer, the atonement is to free a believing captive. If he belonged to a people with whom you have a treaty, compensation must be paid to his family, and a believing captive must be freed. If one lacks the means, fasting for two consecutive months—is a penance from God. God is All-Knowing, All-Wise.