فَإِمَّا تَثْقَفَنَّهُمْ فِي الْحَرْبِ فَشَرِّدْ بِهِم مَّنْ خَلْفَهُمْ لَعَلَّهُمْ يَذَّكَّرُونَ (57)
(8:57) So if you meet them in war, make of them a fearsome example for those who follow them *42 that they may he admonished.
*42). The verse makes it lawful for Muslims to feel absolved of the obligations of a treaty with a people who, despite that alliance, threw the obligations of the treaty overboard and engaged in hostile actions against the Muslims. It would even be lawful for the Muslims to engage in hostilities against them. Likewise, if the Muslims are engaged in hostilities against a people and the non-Muslims who are bound in treaties of alliance or friendship with the Muslims, array themselves on the side of the enemy and fight against the Muslims, it would he lawful for the Muslims to treat them as enemies and kill them. For by their brazen violation of the obligations of the treaty concluded with their people, they had made it absolutely lawful for Muslims to disregard the terms of that treaty concerning the inviolability of the lives and properties of at least those individuals.