Sura 2 Al-Baqarah (The Cow), ayah 6

1. إِنَّ الَّذِينَ كَفَرُوا سَوَاءٌ عَلَيْهِمْ أَأَنْذَرْتَهُمْ أَمْ لَمْ تُنْذِرْهُمْ لَا يُؤْمِنُونَ

   Indeed, those who disbelieve - it is all the same for them whether you warn them or do not warn them - they will not believe.

   2:6

Translation: Saheeh International