Surah An-Nisa' (The Women), Verse 64

وَمَاۤ اَرْسَلْنَا مِنْ رَّسُوْلٍ اِلَّا لِیُطَاعَ بِاِذْنِ اللّٰهِ وَلَوْ اَنَّهُمْ اِذْ ظَّلَمُوْۤا اَنْفُسَهُمْ جَآءُوْكَ فَاسْتَغْفَرُوا اللّٰهَ وَاسْتَغْفَرَ لَهُمُ الرَّسُوْلُ لَوَجَدُوا اللّٰهَ تَوَّابًا رَّحِیْمًا ۟

Wa maa arsalnaa mir Rasoolin illaa liyutaa'a bi iznil laah; wa law annahum 'iz zalamooo anfusahum jaaa'ooka fastaghfarul laaha wastaghfara lahumur Rasoolu la wajadul laaha Tawwaabar Raheemaa

“We sent not a messenger, but to be obeyed, in accordance with the will of Allah. If they had only, when they were unjust to themselves, come unto thee and asked Allah's forgiveness, and the Messenger had asked forgiveness for them, they would have found Allah indeed Oft- returning, Most Merciful.”

Quran 4:64 (Yusuf Ali Translation)