Why were Eid al-Fitr and Eid al-Adha legislated in Islam?

The Eids in Islam are limited to two days: Eid al-Fitr and Eid al-Adha. Allah has replaced them for us with something better than the festivals of the pre-Islamic era. Following Eid al-Adha are the three days of Tashreeq, which also become days of Eid for Muslims. Eid al-Fitr is associated with the end of the Ramadan fast, during which the Qur’an was revealed, as a thank you to Allah for revealing the Qur’an and for enabling us to fast. Eid al-Adha is associated with the Day of Arafah, when the religion was perfected and the favor was completed, and it is an expression of gratitude to Allah for that.