Qur'ān 36:10 · Ya-Sin (يس)

وَسَوَآءٌ عَلَيْهِمْ ءَأَنذَرْتَهُمْ أَمْ لَمْ تُنذِرْهُمْ لَا يُؤْمِنُونَ

And it is all the same for them whether you warn them or do not warn them - they will not believe.