Surah Ar-Rum (The Romans), Verse 60

فَاصْبِرْ اِنَّ وَعْدَ اللّٰهِ حَقٌّ وَّلَا یَسْتَخِفَّنَّكَ الَّذِیْنَ لَا یُوْقِنُوْنَ 

Fasbir inna wa'dal laahi haqqunw wa laa yastakhif fannakal lazeena laa yooqinoon

“So patiently persevere: for verily the promise of Allah is true: nor let those shake thy firmness, who have (themselves) no certainty of faith.”

Quran 30:60 (Yusuf Ali Translation)