So have patience (O Muhammad)! Allah’s promise is the very truth, and let not those who have no certainty make thee impatient.
(English - Pickthal)
Surah Ar-Room, Verse 60:
فَاصْبِرْ إِنَّ وَعْدَ اللَّهِ حَقٌّ وَلَا يَسْتَخِفَّنَّكَ الَّذِينَ لَا يُوقِنُونَ
So be patient (O Muhammad SAW). Verily, the Promise of Allah is true, and let not those who have no certainty of faith, discourage you from conveying Allah’s Message (which you are obliged to convey)
(English - Mohsin Khan)