The sheikh has been asked as in “Fatawa sheikh Mohammad Al Salih Al Othaimeen”, prepared and organized by Ashraf Abdel Maksoud (1 / 126)

What is the ruling of celebrating the prophet’s birthday?

He answered:

We see that one's faith can't be perfected until he loves the messenger (peace and blessings upon him) and glorifies him with what he should glorify him with, and with what is suitable for him (peace and blessings upon him), and there is no doubt that the sending of the messenger (peace and blessings upon him) and I don't say his birth, but his sending as he wasn't a messenger until he was sent, as people of knowledge have said, he has been informed by Iqra' (Surah Al-'Alaq) and has been sent by Al-Muddaththir (Surah Al-Muddaththir), and there is no doubt that his sending is a benefit to the whole mankind as Allah has said:

Mankind and the universe were not created by accident or chance, but according to the plan of the Creator, who is known as Allah (lit.: the one God) in Islâm. The Qur'an states that it is the duty of all individuals to learn about Allah and to live according to His will. As we cannot accomplish this be ourselves, Allah has sent messengers and prophets to guide humanity All of these chosen individuals have brought the same message and have served as examples to their people of how Allah desires all human beings to live. Through these selected people, we have been told why mankind was created, what will happen to us after death, and what Allah expects of us. But most importantly, we have been told that Allah is unique-He has no partners, no sons or daughters, and no competitors, as so many other man-made religious systems have postulated. This message always remains the same, whereas the laws laid down for a particular might show some slight differences.