The question is should we Celebrate Eid Milad Un Nabi SAW? to know that we will have to look back in the history that whether Prophet SAW himself celebrated his birthday? Or His Companions celebrated his birthday?? the answer is simply no. Prophet SAW or his Sahaba never celebrated their birthdays. There are only two Eids in Islam according to Quran and Sunnah that are Eid Ul Adha and Eid Ul Fitr.
Eid Milad Un Nabi is a new invention whose no reference is available in Quran or Hadith. Prophet Muhammad SAW has clearly prohibited to invent any new thing in Islam and called it bid’ah. Rasool Allah SAW said Every innovation is a misguidance and every misguidance goes to Hell fire.
The sad fact of today's Muslim Ummah is that many of us has started doing many new works in name of Islam that are no where present in Quran or Hadith but the important things about which Quran and Hadith have guided us again and again are not followed by us. May Allah SWT help us to follow the real Islam that was given by our beloved Prophet SAW.