Al-Kahf 20

إِنَّهُمْ إِن يَظْهَرُوا۟ عَلَيْكُمْ يَرْجُمُوكُمْ أَوْ يُعِيدُوكُمْ فِى مِلَّتِهِمْ وَلَن تُفْلِحُوٓا۟ إِذًا أَبَدًا

innahum in yaẓharū ʿalaykum yarjumūkum aw yuʿīdūkum fī millatihim walan tuf'liḥū idhan abadan

Indeed, if they come to know of you, they will stone you or return you to their religion. And never would you succeed, then - ever."