The sacrifice of an animal has always been a recognised form of worship in many religions, but in the ‘Shariah’ (Islamic sacred law) of our beloved Prophetpeace and blessings be upon him the sacrifice of an animal has been recognised as a form of worship only during the three days of the month Zulhijjah, namely the 10th, 11th, and 12th .

Allah Ta’ala says in the Noble Quran:

"Verily, We have granted you (O Muhammad peace and blessings be upon him) Al- Kauthar (a river in paradise),

So pray on to thy lord and sacrifice. For he who makes you angry will be cut off."
(Surah 10
"And the camels! We have appointed them among the ceremonies of Allah, therein ye have good!"

Of all of the physical and spiritual worships the greatest is ‘salaah’, and among the worships concerning wealth, sacrifice holds a distinguished position, because the original spirit of sacrifice was to sacrifice the soul. The replacement of an animal was made due to some reasons, as it is clear from the story of Hazrat Ibrahim peace and blessings be upon him and Hazrat Ismail peace and blessings be upon him. That is why in other places in the Quran the mention of ‘salaah’ is made together with ‘Qurbani’. (Tafseer-E-Usmaani)