Surah Aali Imran (The Family of Imran), Verse 144

وَمَا مُحَمَّدٌ اِلَّا رَسُوْلٌ قَدْ خَلَتْ مِنْ قَبْلِهِ الرُّسُلُ اَفَاۡىِٕنْ مَّاتَ اَوْ قُتِلَ انْقَلَبْتُمْ عَلٰۤی اَعْقَابِكُمْ وَمَنْ یَّنْقَلِبْ عَلٰی عَقِبَیْهِ فَلَنْ یَّضُرَّ اللّٰهَ شَیْـًٔا وَسَیَجْزِی اللّٰهُ الشّٰكِرِیْنَ ۟

Wa maa Muhammadun illaa Rasoolun qad khalat min qablihir Rusul; afa'im maata aw qutilan qalabtum 'alaaa a'qaabikum; wa mai yanqalib 'alaa aqibaihi falai yadurral laaha shai'aa; wa sayajzil laahush shaakireen

“Muhammad is no more than a messenger: many Were the messenger that passed away before him. If he died or were slain, will ye then Turn back on your heels? If any did turn back on his heels, not the least harm will he do to Allah; but Allah (on the other hand) will swiftly reward those who (serve Him) with gratitude.”

Quran 3:144 (Yusuf Ali Translation)