What is the ruling regarding those who celebrate the birthday of the Prophet, sallallaahu 'alayhi wa sallam?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

Allaah The Almighty Says (what means): {Say, [O Muhammad], "If you should love Allaah, then follow me, [so] Allaah will love you and forgive you your sins.} [Quran 3:31] In a narration on the authority of ‘Aa’ishah the Prophet stated that whoever introduces something new in Islam which does not belong to it, it will be rejected and Allaah will not accept it from him. [Al-Bukhari and Muslim]

Jaabir ibn `Abdullaah, said that the Prophet used to say in the introduction of his sermons that the best words are those in the Book of Allaah The Almighty, the best guidance is that of Muhammad , the worst of all deeds is innovating in the matters of religion and that every religious innovation is misguidance. [Muslim]

There is no authentic narration from the Prophet or the rightly-guided Caliphs stating that they used to celebrate Al-Mawlid (the birthday of the Prophet ), or anything to that effect. If the celebration of his birthday was a good thing, the companions would have been the pioneers in doing so.

For the purpose of preserving the noble Sunnah and abiding by the Quran, Muslims should not introduce any matter that does not belong to the Book of Allaah (the Quran) or the Sunnah of the Prophet and should not busy themselves with such innovated matters as this would result in failing to apply the Sunnah and convey the message of the Prophet .

It is not permissible for any Muslim, regardless of his status, to propagate religious innovations or practice them, as stated by the righteous predecessors of this Ummah and affirmed by the diligent and prominent Imaams .

Finally, we implore Allaah The Almighty to guide us to follow in their footsteps and hold fast to the straight path without addition or deletion.  

Allaah Knows best.