Is it permissible to celebrate the BIRTHDAY of PROPHET MUHAMMAD [SAW]? If yes, I would like to have some evidences.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Celebrating the birthday of the Prophet Muhammad is an innovation in Islam. There is no evidence for it in the Islamic Sharee’ah. The Fatimids were the first to innovate this innovation. However, this is not evidence of loving the Prophet Muhammad . Instead of this, a person should follow what the Prophet commanded, believe in what he conveyed, avoid forbidden matters and worship Allah as He and His Prophet prescribed. These acts constitute real evidence of loving the Prophet .  In this regard, Allah Says (what means): {Say, [O Muhammad sallallaahu ‘alayhi wa sallam], “If you should love Allah, then follow me, [so] Allah will love you and forgive you your sins. And Allah is Forgiving and Merciful.”} [Quran 3:31] On the other hand, celebrating the birthday of the Prophet or the new Hijira year or other celebrations other than the two ‘Eeds of Al-Fitr and Al-Adhha is among the invented celebrations and feasts. It is confirmed that the Prophet said: “Whoever introduces into this matter of ours (Islam) that which is not a part of it; it will be rejected.” [Al-Bukhari]

As regards the biography of honorable Hassan Ibn Ali  we advise you to refer to the well-known book "Siyar A'laam An-Nubala’ by Imaam Ath-Thahabi . We also advise you to read the summarized book Minhaaj as-Sunnah an-Nabawiyyah by Imaam Ath-Thahabi or by Shaykh ‘Abdullah Al-Ghunaymaan.

Allah knows best.