144وَمَا مُحَمَّدٌ إِلَّا رَسُولٌ قَدْ خَلَتْ مِن قَبْلِهِ ٱلرُّسُلُ ۚ أَفَإِي۟ن مَّاتَ أَوْ قُتِلَ ٱنقَلَبْتُمْ عَلَىٰٓ أَعْقَـٰبِكُمْ ۚ وَمَن يَنقَلِبْ عَلَىٰ عَقِبَيْهِ فَلَن يَضُرَّ ٱللَّهَ شَيْـًٔا ۗ وَسَيَجْزِى ٱللَّهُ ٱلشَّـٰكِرِينَ
[144] Muhammad is no more than a Messenger: other Messengers have already passed before him: if, then, he also dies or is slain, will you then turn about on your heels?103 Remember, he, who turns about on his heels, will do no harm at all to Allah; of course Allah will duly reward those who live as His grateful servants.
103This is the answer to the mischievous talk of those hypocrites who had accompanied the Muslims in the battle of Uhd. When the rumour spread that the Holy Prophet had been slain, naturally the we Muslims lost heart, but the hypocrites began to say, "Let us go to `Abdullah bin Ubayy and request him to obtain amnesty for us from Abu Sufyan. " Others who were more impudent, went even so far as to say, "If Muhammad (Allah's peace be upon him) had been a true Prophet of Allah, he could not have been slain. Let us now turn to our ancestral Faith." Allah rebukes them as if to say, "Muhammad (Allah's peace be upon him) is a Prophet, and is mortal like other Prophets who came before him: therefore, if your attachment to Islam is because of the person of Muhammad (Allah's peace be upon him), and if it stands on such flimsy ground that with his death you will again return to disbelief, then Allah's religion does not stand in need of you."
This verse was also meant to impress that Muhammad (Allah's peace be upon him) was mortal like all other Prophets. According to a tradition, on the morning when the Prophet died, Abu Bakr came into the mosque at Al-Madinah and found the people all distracted, and `Umar telling them that it was a sin to say that he was dead. Abu Bakr went and ascertained the truth, and coming back into the mosque, cried, "Lo! as for him who worshipped Muhammad, Muhammad (Allah's peace be upon him) is dead, but as for him who worships Allah, Allah is alive and does not die." Then he recited this verse "and it was as if the people had not known till then that such a verse had been revealed."