Eid-ul-Adha

Eid ul Adha

Eid al-Adha is an important religious holiday celebrated by Muslims worldwide to honor the willingness of the prophet Ibrahim (Abraham) to sacrifice his young first-born son Ismail (Ishmael)a as an act of submission to God's command and his son's acceptance to being sacrificed, before God intervened to provide Abraham with a Lamb to sacrifice instead.
Al-Quran:_
[Saffat 37:102] And when he became capable of working with him, Ibrahim said, “O my son, I dreamt that I am sacrificing you - therefore now consider what is your opinion”; he said, “O my father! Do what you are commanded! Allah willing, you will soon find me patiently enduring!”
[Saffat 37:103] Then (remember) when they both submitted to Allah’s command, and Ibrahim lay his son facing downwards. (The knife did not hurt Ismail)
[Saffat 37:104] And We called out to him, “O Ibrahim!”
[Saffat 37:105] “You have indeed made the dream come true”; and this is how We reward the virtuous.
[Saffat 37:106] Indeed this was a clear test.
[Saffat 37:107] And We rescued him in exchange of a great sacrifice.
(The sacrifice of Ibrahim and Ismail – peace be upon them – is commemorated every year on 10,11 and 12 Zil Haj).

In the lunar Islamic calendar, Eid al-Adha falls on the 10th day of Zul-Hijjah and lasts for four days. In the international Gregorian calendar, the dates vary from year to year, drifting approximately 11 days earlier each year. Eid al-Adha is the latter of the two Eid holidays, the former being Eid al-Fitr. Like Eid al-Fitr, Eid al-Adha begins with a Sunnah prayer of two rakats followed by a sermon (khuṭbah). Eid al-Adha celebrations start after the descent of the Hajj from Mount Arafat, a hill east of Mecca. Ritual observance of the holiday lasts until sunset of the 12th day of Dhu al-Hijjah. Eid sacrifice may take place until sunset on the 13th day of Dhu al-Hijjah. The days of Eid have been singled out in the Hadith as "days of remembrance". The days of Tashriq are from the Fajr prayer of the 9th of Dhul Hijjah up to the Asr prayer of the 13th of Dhul Hijjah (5 days and 4 nights). This equals 23 prayers: 5 on the 9th-12th, which equal 20, and 3 on the 13th.
Sources:

www.alahazrat.net/alquran
www.en.wikipedia.org/