Quran 9, Al-Tawba (Repentance) ⓘ

9:12And 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.

وَإِنْ نَكَثُوا أَيْمَانَهُمْ مِنْ بَعْدِ عَهْدِهِمْ وَطَعَنُوا فِي دِينِكُمْ فَقَاتِلُوا أَئِمَّةَ الْكُفْرِ إِنَّهُمْ لَا أَيْمَانَ لَهُمْ لَعَلَّهُمْ يَنْتَهُونَ