What is the ruling on celebrating the birth of the Prophet, peace and blessings be upon him, and holding it on every occasion such as giving thanks, marriage, or the seventh day of a newborn, and what is the refutation against those who say that it is for reminding people of the Prophet's biography?

Celebrating the birth of the Prophet, peace be upon him, or anyone else, is not from the guidance of the Prophet nor his Companions. Worship is based on divine instruction. Therefore, every act of worship that the Prophet, peace be upon him, abandoned despite the presence of a reason for it and the absence of an impediment to it, performing it is a reprehensible innovation (bid'ah). The reason for such a celebration was present during his time, peace be upon him, and during the time of the Rightly Guided Caliphs, yet they did not do it. As for reminding people of the Prophet's biography, peace be upon him, this is done by teaching and explaining it in mosques and educational institutions, not through celebrations that may involve violations of Islamic law.