Quran 2.192-194
But if they desist, then lo! Allah is Forgiving, Merciful. And fight them until persecution is no more, and religion is for Allah. But if they desist, then let there be no hostility except against wrong-doers. The forbidden month for the forbidden month, and forbidden things in retaliation. And one who attacketh you, attack him in like manner as he attacked you. Observe your duty to Allah, and know that Allah is with those who ward off (evil).