I have been told that celebrating birthdays is tantamount to innovation in the religion of God. The following saying of the Holy Prophet (sws) is quoted to prove this claim.
Whoever introduces anything into this matter of ours that does not belong to it shall have that action rejected. (Bukhari, Muslim).
In another version recorded by Muslim and by Bukhari, the wording is as follows:
Whoever performs a deed which is not in accord with our affairs, then that deed is rejected.
These people maintain that the Holy Prophet (sws) did not celebrate his birthday at all during his lifetime nor did he ever order it to be celebrated. He also did not teach this to his Companions (rta). Therefore, the rightly-guided caliphs and all of his Companions (rta) did not celebrate it. They were the most knowledgeable of the people concerning his Sunnah and they were the most beloved to the Holy Prophet (sws). Therefore, if one is supposed to celebrate the Holy Prophet (sws)’s birthday, this would have been made evident at their time. Similarly, not one of the scholars of the best generations celebrated his birthday nor did they order it to be done. The absence of the celebration with the Companions (rta) and the most learned scholars of the past would mean that such a celebration is not from the Law that Allah sent Muhammad (sws) with