وَمَامُحَمَّدٌإِلَّارَسُولٌقَدْخَلَتْمِنْقَبْلِهِالرُّسُلُۚأَفَإِنْمَاتَأَوْقُتِلَانْقَلَبْتُمْعَلَىٰأَعْقَابِكُمْ
Wamā Muhammadun illā rasūlun qad khalat min qablihil-rusul. Afa-in māta aw qutilan-qalabtum ‘ala a‘qābikum
And Muhammad is no more than a messenger; the messengers have already passed away before him; if then he dies or is killed will you turn back upon your heels?
(Sūrat Āli Imrān, No. 3, Āyat 144)
This verse was revealed after the battle of ‘Uhud when there was a rumor that the Holy Prophet (s) had been killed. People panicked when they heard that. Many fled the scene while others contemplated joining the opposite forces now that the Prophet was dead. Only a small group stood firm and invited the others towards reason. If Muhammad (a) was dead, said Anas bin Nadhīr one of the companions, the God of Muhammad was not dead.
The above verse explains to the Muslims that the religion of Islam worships God, not a person. Even a person as great as the Holy Prophet (s) was still only a servant and a Messenger of God. There were other Prophets who had been sent before him who died and left the world. If the Prophet were to die the duty of the believers would be to continue his mission and keep it alive.
It is a sign of the authenticity of the Holy Prophet (s) that he did not let the Muslims think that the religion of Islam was linked to him alone. Islam was bigger than that. It was all to do with God, not any one human being. That type of leadership reveals a true sincerity far removed from the ego battles that often taint leadership.
Bibi Fātima (a) recited this verse as part of her sermon on Fadak, the land which she had received from her father and which was denied to her. She asked why the Muslims did not speak up for her rights. She (a) said:
Do you then say that Muhammad has passed away and there remains no responsibility upon us? His loss is great . . . and there is no other greater calamity than the death of the Prophet!. . . This (the death of the Prophet) had already been conveyed to you in the Book of Allah, may He be glorified. You were reading the Qurʾan day and night in a loud voice, lamentingly, in a normal tone and in a pleasant voice. As for what happened in the past to Allah’s prophets and apostles – the command is decisive and destiny enjoined. And Muhammad is not but an apostle, (other) apostles have already passed away prior to him, therefore if he dies or is killed, will you turn upon your heels?
The message in this verse is that Islam should not be used for personal gain and status. The goals of Islam are much higher. Raising of personalities without regard for the actual rules is a sign of deviance from the true message of Islam. Islam will always be elevated, immune from the coming and going of leaders. Muslims need to understand that and serve it to continue the mission.
Sources: Āyatullāh Nāsir Makārim Shirāzī (ed.), Tafsīr-e Namūne. http://www.al-islam.org/fatimiyyah-ashura-lutfullah-safi-al-gulpaygani/historic-fadak-sermon-fatima