"Verily, Allah has purchased of the believers their lives and their properties; for the price that theirs shall be the Paradise. They fight in Allah's Cause, so they kill (others) and are killed. It is a promise in truth which is binding on Him in the Taurat (Torah) and the Injeel (Gospel) and the Quran. And who is truer to his covenant than Allah? Then rejoice in the bargain which you have concluded. That is the supreme success. (111) "
Surat Al Maidah
"And what is wrong with you that you fight not in the Cause of Allah, and for those weak, ill-treated and oppressed among men, women, and children, whose cry is: "Our Lord! Rescue us from this town whose people are oppressors; and raise for us from You one who will protect, and raise for us from You one who will help." (75) Those who believe, fight in the Cause of Allah, and those who disbelieve, fight in the cause of Taghut (Satan, etc.). So fight you against the friends of Shaitan (Satan); Ever feeble indeed is the plot of Shaitan (Satan). (76)"
Surat Anisaa
"Permission to fight is given to those (i.e. believers against disbelievers), who are fighting them, (and) because they (believers) have been wronged, and surely, Allah is Able to give them (believers) victory (39) "
Surat Al Hajj
"And We ordained therein for them: "Life for life, eye for eye, nose for nose, ear for ear, tooth for tooth, and wounds equal for equal." But if anyone remits the retaliation by way of charity, it shall be for him an expiation. And whosoever does not judge by that which Allah has revealed, such are the Zalimun (polytheists and wrong-doers - of a lesser degree). (45)"
Surat Al Maidah