It is not permissable to celebrate the birthday of the prophet (sallalahu alayhi wasallam) as celebrating birthdays is an innovation in the religion. The prophet (sallallahu alayhi wasallam) did not celebrate his birthday at any time in his life, and he was the conveyor of this religion and carried out the rulings conveyed to him from his lord, the Most Glorified. And he did not command others to celebrate it, neither the righteous caliphs or the rest of the companions. And none of the successive generation known as the tabieen celebrated it or those that followed them! And they were the best of mankind and the closest to the prophet in terms of following his example and their love of him. The prophet (sallalahu alayhi wasallam) said: ” the best of mankind is my generation, then those that follow them, then those that follow them.” (bukharee)
So therefore it is a forbidden innovation known as a bidah. And the propet (sallalahu alayhi wasallam) said: ” whoever innovates into this affair of ours that which is not from it, will have it rejected” (Bukharee). And in another wording of Muslim: “whoever performs a deed which is not from this affair of ours, will have it rejected.”
So whether one initiates a new act of worship, or merely imitates an innovated act of worship, it is rejected by Allah since it is not in conformity with the revealed texts. Acts of worship have to be based only upon the Quran and Sunnah, one cannot introduce new acts of worship into the religion. This is due to the fact that our religion has been perfected and completed, as Allah has said:
“this day I have perfected your religion for you, completed my favour upon you and I am pleased with islam as your religion.” (5:3)
that which has been completed and perfected by The Lord of the universe requires no further perfection, completion or addition! Allah forbade any legislation or worship to be added to his completed religion.
“or have they partners alongside Allah who have legislated for them from the religion that which Allah has not ordained” (42:21)
So celebrating the birthday of the prophet is a newly invented religious act, which does not conform with the texts of the Quran and Sunnah. It was innovated into this pure religion centuries after the passing away of Allahs messenger (sallalahu alayhi wasallam) who used to say during his Friday sermon:
“Verily, the best speech is the book of Allah, and the best guidance is the guidance of the Muhammad, and the worst of all affairs are the newly invented matters (in religion), and every innovation is misguidance. And every misguidance is in the fire.” (Muslim and Nisaa’ee)
If celebrating the prophets birthday was legislated, the earlier generations would have been the first to celebrate it, since they were the best of generations and the closest to the noble prophet and the most beloved to him from mankind. The companions would have been the first to celebrate it had it been legislated or something good, and they would have called others to it, and the knowledge of it would be present in their authentically reported statements and actions. Yet, this celebration was unknown to the earliest three generations of noble believers, and is rejected by religious text. So a muslim should keep away from these newly invented celebrations as they don’t bring you closer to Allah or increase you in goodness.