At-Taubah - 9:12

وَإِن نَّكَثُواْ أَيْمَانَهُم مِّن بَعْدِ عَهْدِهِمْ وَطَعَنُواْ فِي دِينِكُمْ فَقَاتِلُواْ أَئِمَّةَ الْكُفْرِ إِنَّهُمْ لاَ أَيْمَانَ لَهُمْ لَعَلَّهُمْ يَنتَهُونَ
[9:12]
And if they break their oaths after their agreement and (openly) revile your religion, then fight the leaders of unbelief-- surely their oaths are nothing-- so that they may desist.
But if they violate their oaths after their covenant, and taunt you for your Faith,- fight ye the chiefs of Unfaith: for their oaths are nothing to them: that thus they may be restrained.
And if they break their pledges after their treaty (hath been made with you) and assail your religion, then fight the heads of disbelief - Lo! they have no binding oaths - in order that they may desist.