Q: What is the legal ruling on celebrating birthdays?
A: Birthday celebrations have no religious evidence in the purified Shari`ah (Islamic law). They are Bid`ah (innovation in religion). The Prophet (peace be upon him) stated: He who introduces things extraneous to our affair religion, will have them rejected. (Agreed upon by Imams AlBukhari and Muslim)
According to another narration related by Muslim and related by AlBukhari (may Allah be merciful with him) in the form of Mu`allaq (a Hadith missing link in the chain of narration, reported directly from the Prophet) in his Sahih (authentic) book of Hadith, reading: He who does any act for which there is no sanction from our behalf, that is to be rejected.
It is known that the Prophet (peace be upon him) did not celebrate his birthday at all, nor did he order or teach His Companions to do it. Likewise, his RightlyGuided Caliphs and his Companions who are the most knowledgeable of his Sunnah, the dearest to the Prophet (peace be upon him), and most keen to follow his teachings did not.