3:144
وَمَا مُحَمَّدٌ إِلَّا رَسُولٌۭ قَدْ خَلَتْ مِن قَبْلِهِ ٱلرُّسُلُ ۚ أَفَإِي۟ن مَّاتَ أَوْ قُتِلَ ٱنقَلَبْتُمْ عَلَىٰٓ أَعْقَٰبِكُمْ ۚ وَمَن يَنقَلِبْ عَلَىٰ عَقِبَيْهِ فَلَن يَضُرَّ ٱللَّهَ شَيْـًۭٔا ۗ وَسَيَجْزِى ٱللَّهُ ٱلشَّٰكِرِينَ
Muhammad is not but a messenger. [Other] messengers have passed on before him. So if he was to die or be killed, would you turn back on your heels [to unbelief]? And he who turns back on his heels will never harm Allah at all; but Allah will reward the grateful.
Translation · Saheeh International
Tafsir
Ibn Kathīr (abridged)
The Rumor that the Prophet was Killed at Uhud
When Muslims suffered defeat in battle at Uhud and some of them were killed, Shaytan shouted, "Muhammad ﷺ has been killed." Ibn Qami'ah went back to the idolators and claimed, "I have killed Muhammad." Some Muslims believed this rumor and thought that the Messenger of Allah ﷺ had been killed, claiming that this could happen, for Allah narrated that this occurred to many Prophets before. Therefore, the Muslims' resolve was weakened and they did not actively participate in battle. This is why Allah sent down to His Messenger His statement,
وَمَا مُحَمَّدٌ إِلاَّ رَسُولٌ قَدْ خَلَتْ مِن قَبْلِهِ الرُّسُلُ
(Muhammad is no more than a Messenger, and indeed Messengers have passed away before him.) he is to deliver Allah's Message and may be killed in the process, just as what happened to many Prophets before. Ibn Abi Najih said that his father said that a man from the Muhajirin passed by an Ansari man who was bleeding (during Uhud) and said to him, "O fellow! Did you know that Muhammad ﷺ was killed" The Ansari man said, "Even if Muhammad ﷺ was killed, he has indeed conveyed the Message. Therefore, defend your religion." The Ayah,
وَمَا مُحَمَّدٌ إِلاَّ رَسُولٌ قَدْ خَلَتْ مِن قَبْلِهِ الرُّسُلُ
(Muhammad is no more than a Messenger, and indeed (many) Messengers have passed away before him), was revealed. This story was collected by Al-Hafiz Abu Bakr Al-Bayhaqi in Dala'il An-Nubuwwah.