What is an udhiyyah? Why is it legislated and is it obligatory?

Definition of udhiyyah
It is the animal slaughtered in worship of God Almighty on the days specified for slaughtering between 'Eid al-Adha and the last of the three days following it. The udhiyyah must meet sacrifice specifications.

Animals not considered udhiyyah
- Animals slaughtered for any purpose other than for worshiping God Almighty, such as those intended for selling, eating or feeding guests.
- Animals slaughtered on days other than those specified for slaughtering even if intended for the worship of God.
- Animals slaughtered on days other than those between 'Eid al-Adha and the three days following it even if in worship of God.
- Animals slaughtered for 'aqiqa [Ar. sacrifice made for a newborn].
- Animals slaughtered on hajj either for tammattu' [an 'umrah first hajj] or qiran [performing hajj and 'umrah simultaneously].
- Animals slaughtered in expiation for neglecting an obligatory rite or committing a prohibited act during hajj.
- Animals sacrificed with the general purpose of offering meat to the poor in the sacred precinct.

Lexical definition
The word udhiyyah is derived from the term ad-duha [En. midmorning] i.e. the time of day it is offered.

Purpose of legislating the udhiyyah
The udhiyyah was legislated to show gratitude to Allah for the blessing of witnessing the virtuous days of Dhul-Hijjah, and [in commemoration of the sacrifice of Abraham in gratitude to God for sparing the life of his son, Ismail. Likewise, it is an expression of one's gratitude for the success of doing good deeds during these blessed days which are the best of the year and by which God Almighty swears an oath in the Quran: “By the dawn, and by the ten nights” (89:1-2).
Ibn 'Abbas narrated that the Messenger of God (peace and blessings be upon him) said, "No good deeds performed on other days are superior to those performed on these days [the ten days of Dhul-Hijjah]." The companions asked, "O Messenger of God, not even fighting in the way of God [Ar.jihad]?" He said, "Not even jihad, except for the man who puts his life and wealth in danger [for the sake of God] and returns with neither" (recorded by Bukhari and others).

A time to rejoice
Islam teaches its followers to rejoice for the sake of God Almighty and by His grace. 'Eid al-Fitr [the feast celebrating the culmination of the fasting period of Ramadan] and 'Eid al-Adha are times of rejoicing for obeying God and for the success granted by God for doing good deeds and pleasing Him. In this manner, a Muslim becomes accustomed to dedicating all his actions—whether of joy or grief, giving or abstaining, his life and death—to God Almighty.

Scriptural evidence and the consensus of the community
- God Almighty says: “So pray to your Lord and sacrifice [to Him alone]” (Quran 108: 2). This verse means that one must perform the 'Eid prayer and then slaughter the sacrificial animals i.e. camels and other livestock [i.e. cows and sheep].

- The sacrificial rite is both a verbal sunnah [sunnah qawliyyah] and active sunnah [sunnah fi'liyya] i.e. those acts that the Prophet urged Muslims to perform and which he practiced himself.

- Abu Huraira (may God be pleased with him) narrated that the Messenger of God (peace and blessings be upon him) said, "Whosoever has the means and does not offer a sacrifice let him not approach our musalla [place of prayer]" (recorded by Ibn Majah and al-Hakim. Al-Hakim declared it authentic).

- Anas (may God be pleased with him) narrated that the Prophet (peace and blessings be upon him) sacrificed two horned black and white rams. He slaughtered them himself, invoked the name of God upon them and glorified Him and placed his foot on their sides (while sacrificing) (Muslim).

- There is a consensus among Muslims on the legitimacy of the udhiyyah.

Legal Ruling on udhiyyah
- The majority of scholars maintain that it is an established sunnah—a person who does not perform it is not blameworthy though the one who is capable of performing it misses great blessings by neglecting it.

- 'Aisha (may God be pleased with her) narrated that the Prophet (peace and blessings be upon him) said: "There is nothing dearer to God during the days of sacrifice than sacrificing animals. The sacrificed animal will come on the Day of Judgment with its hair, horns and hooves intact. It is accepted by God before its blood reaches the ground. So, make the sacrifice with a consenting heart" (recorded by Ibn Majah, al-Tirmidhi, and al-Hakem. Al-Tirmidhi declared it a fair and singular report and al-Hakem declared it authentic).

- Some scholars, including Abu Hanifa and Malik in one of his two opinions maintained that sacrifice is an obligatory rite.

- Some scholars maintained that it is a sunnat 'ayn [i.e. it earns a reward for only the person performing it]. Others—including the Shafi'is and Hanbalis—maintained that it is both a sunnat 'ayn for the person making it on his own behalf and a sunnat kifaya [collective sunnah] the reward of which extends to the members of the household of the person performing it. We are in favor of this opinion; an individual is to offer a sacrificial animal for himself and on behalf of his family, even with only one sheep. Abu Ayub al-Ansari said: "We used to sacrifice one sheep, and a man would offer a sacrifice for himself and his family. Later on, people began to compete with each other and it became a matter to boast about" (recorded by Malik. Al-Nawawi declared it authentic in his Majmu').

- The members of a person's family are his dependents. The fact that this rite is a sunnah means that it is fulfilled when performed by a single member of the family. The rest of the members do not share its reward except if the person making the sacrifice makes the intention of including them in it.

And God Almighty knows best.