At-Tawbah 9:12

Wa-in nakathoo aymanahum min baAAdiAAahdihim wataAAanoo fee deenikum faqatilooa-immata alkufri innahum la aymana lahumlaAAallahum yantahoon

And if they break their oaths after their treaty and defame your religion, then combat the leaders of disbelief, for indeed, there are no oaths [sacred] to them; [fight them that] they might cease.

And if they break their oaths after they have made a covenant, and speak evil of your Faith, then fight the leaders of infidelity,-since their oaths are nothing,-so that they may desist,