Quran 4:91 — Women (Al-Nesa')

You will find others who wish to make peace with you, and also with their people. However, as soon as war erupts, they fight against you. Unless these people leave you alone, offer you peace, and stop fighting you, you may fight them when you encounter them. Against these, we give you a clear authorization.

[4:90] Exempted are those who join people with whom you have signed a peace treaty, and those who come to you wishing not to fight you, nor fight their relatives. Had GOD willed, He could have permitted them to fight against you. Therefore, if they leave you alone, refrain from fighting you, and offer you peace, then GOD gives you no excuse to fight them.

[4:92] No believer shall kill another believer, unless it is an accident. If one kills a believer by accident, he shall atone by freeing a believing slave, and paying a compensation to the victim's family, unless they forfeit such a compensation as a charity. If the victim belonged to people who are at war with you, though he was a believer, you shall atone by freeing a believing slave. If he belonged to people with whom you have signed a peace treaty, you shall pay the compensation in addition to freeing a believing slave. If you cannot find* a slave to free, you shall atone by fasting two consecutive months, in order to be redeemed by GOD. GOD is Knower, Most Wise.