The word udhiyah means an animal of the ‘an’aam class (i.e., camel, cow, sheep or goat) that is slaughtered during the days of Eid al-Adha because of the Eid and as an act of worship, intending to draw closer to Allaah thereby .
Al-Udhiyah (the offering of a blood sacrifice) is one of the great rituals of Islam, in which we remember the oneness of Allaah, His blessings upon us and the obedience of our father Ibraaheem to his Lord, and in this act of udhiyah there is great benefit and blessing. So the Muslim must pay attention to its great importance. The following is a brief look at this important ritual. Al-Udhiyah refers to the animal (whether a camel, cow or sheep) that is sacrificed as an act of worship to Allaah, in the country in which the person offering the sacrifice lives, during the period from after the Eid prayer on the Day of Nahr (Eid al-Adhaa) until the last of the Days of Tashreeq (the 11th, 12th and 13th day of
Dhu’l-Hijjah), with the intention of offering sacrifice .
This is one of the rituals of Islam prescribed in the Book of Allaah and the Sunnah of His Messenger (peace and blessings of Allaah be upon him), and according to the consensus of the Muslims.
In the Qur’aan:
1 ‒ Allaah says (interpretation of the meaning): “Therefore turn in prayer to your Lord and sacrifice (to Him only)”[al-Kawthar 108:2]
2 ‒ Allaah says (interpretation of the meaning): “Say (O Muhammad): Verily, my Salaah (prayer), my sacrifice, my living, and my dying are for Allaah, the Lord of the ‘Aalameen (mankind, jinn and all that exists). He has no partner. And of this I have been commanded, and I am the first of the Muslims” [al-An’aam 6:162]
The word nusuk (translated here as sacrifice) means sacrifice; this is the view of Sa’eed ibn Jubayr. And it was said that it means all acts of worship, including sacrifice, which is more comprehensive.
3 ‒ Allaah says (interpretation of the meaning): “And for every nation We have appointed religious ceremonies, that they may mention the Name of Allaah over the beast of cattle that He has given them for food. And your Ilaah (God) is One Ilaah (God Allaah), so you must submit to Him Alone (in Islam). And (O Muhammad) give glad tidings to the Mukhbitoon [those who obey Allaah with humility and are humble from among the true believers of Islamic Monotheism]” [al-Hajj 22:34]
In the Sunnah:
1 ‒ It was narrated in Saheeh al-Bukhaari (5558) and Saheeh Muslim (1966) that Anas ibn Maalik (may Allaah be pleased with him) said: “The Prophet (peace and blessings of Allaah be upon him) sacrificed two white rams speckled with black. He slaughtered them with his own hand, said ‘Allaahu akbar’ and put his foot on their necks.”
2 ‒ It was narrated that ‘Abd-Allaah ibn ‘Umar (may Allaah be pleased with him) said: “The Prophet (peace and blessings of Allaah be upon him) stayed in Madeenah for ten years, offering sacrifice (every year on Eid).” Narrated by Ahmad, 4935; al-Tirmidhi, 1507; classed as hasan by al-Albaani in Mishkaat al-Masaabeeh, 1475.
3 ‒ It was narrated from ‘Uqbah ibn ‘Aamir (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) shared out sacrificial animals amongst his companions, and ‘Uqbah got a sheep that was six months
old. He said, “O Messenger of Allaah, I got a sheep that is six months old.” He said, “Offer it as a sacrifice.” Narrated by al-Bukhaari, 5547.
4 ‒ It was narrated from al-Baraa’ ibn ‘Aazib (may Allaah be pleased with him) that the Prophet (peace and blessings of
Allaah be upon him) said: “Whoever offers a sacrifice after the prayer has completed his rituals (of Eid) and has followed the way of the Muslims.” Narrated by al-Bukhaari, 5545.
The Prophet (peace and blessings of Allaah be upon him) offered sacrifices, as did his companions (may Allaah be pleased with them). And he said that sacrifice is the way of the Muslims. Hence the Muslims are unanimously agreed that it is prescribed in Islam, as was narrated by more than one of the scholars. But they differed as to whether it is Sunnah mu’akkadah (a confirmed Sunnah) or it is obligatory and it is not permissible to omit it.
The majority of scholars are of the view that it is Sunnah mu’akkadah. This is the view of al-Shaafa’i, Maalik and Ahmad
according to his most well-known view. Others were of the view that it is obligatory. This is the view of Abu Haneefah and one of the views narrated from Ahmad. This was also the view favoured by Ibn Taymiyah who said: “This is one of the views narrated in the madhhab of Maalik, or it appears to be the view of Maalik.” From Risaalat Ahkaam al-Udhiyah
wa’l-Dhakaah by Ibn ‘Uthaymeen (may Allaah have mercy on him).
Shaykh Muhammad ibn ‘Uthaymeen (may Allaah have mercy on him) said: “Udhiyah is Sunnah mu’akkadah for the one who is able to do it, so a person should offer the sacrifice on behalf of himself and the members of his household.”
Fataawa Ibn ‘Uthaymeen, 2/661 
 Definition of udhiyah and ruling thereon - IslamQA
 Rulings of Udhiyah (Sacrifice) - Sheikh Muhammad Salih al-Munajjid
A sheep suffices as a sacrifice for one man and the members of his household and his children, because of the hadeeth of Abu Ayyoob:
“At the time of the Messenger of Allaah (peace and blessings of Allaah be upon him), a man would sacrifice a sheep on behalf of himself and the members of his household, and they would eat from it and give some of it to others.” (Reported by Ibn Maajah and al-Tirmidhi, who classed it as saheeh)
The kinds of animals prescribed for sacrifice are camels, cows and sheep. Some of the scholars said that the best sacrifice is camels, then cows, then sheep, then a share in a she-camel or cow, because the Prophet (peace and blessings of Allaah be upon him) said concerning Friday prayers:
“Whoever goes to [Friday prayers] early, it is equivalent to him sacrificing a camel.” This is the opinion of the three imaams Abu Haneefah, al- Shaafa'i and Ahmad. On this basis, a sheep is better than one seventh of a camel or cow. Maalik said that the best is a young sheep, then a cow then a camel, because the Prophet (peace and blessings of Allaah be upon him) sacrificed two rams, and he never did anything but that which was the best. The response to
that is that he (peace and blessings of Allaah be upon him) always chose what was more appropriate out of kindness towards his ummah, because they would follow his example, and he did not want to make things difficult for them. (Fataawa al-Shaykh ‘Abd al-‘Azeez ibn Baaz).
A camel or cow suffices for seven people, because of the report narrated by Jaabir (may Allaah be pleased with him) who said: “We sacrificed at al-Hudaybiyah with the Prophet (peace and blessings of Allaah be upon him), a camel for
seven and a cow for seven.” According to one version: “The Messenger of Allaah (peace and blessings of Allaah be upon him) commanded us to share camels and cattle, each seven men sharing one animal.”
According to another version: “So a cow would be sacrificed on behalf of seven men and we would share it.” (Reported by Muslim)
"Rulings of Udhiyah" by Muhammad Salih al-Munajjid
The animal should have reached the required age, which is six months for a lamb, one year for a goat, two years for a cow and five years for a camel. It should be free of any faults, because the Prophet (peace and blessings of Allaah be upon him) said:
“There are four that are unacceptable for sacrifice: a one-eyed animal whose defect is obvious, a sick animal
whose sickness is obvious, a lame animal whose limp is obvious and an emaciated animal that has no marrow in
its bones.” (Saheeh, Saheeh al-Jaami’, no. 886).
There are milder defects that do not disqualify an animal, but it is makrooh to sacrifice such animals, such as an animal with a horn or ear missing, or an animal with slits in its ears, etc. Udhiyah is an act of worship to Allaah, and Allaah is Good and accepts only that which is good. Whoever honours the rites of Allaah, that is a sign of the piety (taqwa) of the heart.
It is forbidden to sell it. If an animal has been selected for sacrifice, it is not permissible to sell it or give it away, except in exchange for one that is better. If an animal gives birth, its offspring should be sacrificed along with it. It is also permissible to ride it if necessary. The evidence for this is the report narrated by al-Bukhaari and Muslim from Abu Hurayrah (may Allaah be pleased with him), who said:
“The Messenger of Allaah (peace and blessings of Allaah be upon him) saw a man leading his camel and told him, “Ride it.” He said, “It is for sacrifice.” He said, “Ride it” a second or third time.”
It should be sacrificed at the specified time, which is from after the prayer and khutbah of Eid – not from when the time for the prayer and khutbah starts – until before sunset on the last of the days of Tashreeq, which is the 13th day of Dhu’l-Hijjah. The Prophet (peace and blessings of Allaah be upon him) said: “Whoever sacrifices before the prayer, let him repeat it.” (Reported by al-Bukhaari and Muslim).
‘Ali (may Allaah be pleased with him) said: “The days of Nahr (Sacrifice) are the day of al-Adhaa and the three days following it.” This is also the opinion of al-Hasan al-Basri, ‘Ata’ ibn Abi Rabaah, al-Oozaa’i, al-Shaafa'i and Ibn al-Mundhir, may Allaah have mercy on them all.
"Ruling of the Udhiyah" by Muhammad Salih al-Munajjid
The time for offering the sacrifice begins after the Eid prayer on Eid al-Adha and ends when the sun sets on the thirteenth of Dhu’l-Hijjah. So there are four days of sacrifice: the day of Eid al-Adha and the three days after it.
It is better to hasten to offer the sacrifice after the Eid prayer, as the Messenger (peace and blessings of Allaah be upon him) used to do, then the first thing he would eat on the day of Eid would be meat from his sacrifice.
Ahmad (22475) narrated that Buraydah (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) did not go out on the day of (Eid) al-Fitr until he had eaten, and he did not eat on the day of (Eid) al-Adha until he came back, then he would eat from his sacrifice.
Al-Zayla’i narrated in Nasb al-Raayah (2/221) that Ibn al-Qattaan classed it as saheeh.
Ibn al-Qayyim (may Allaah have mercy on him) said in Zaad al-Ma’aad (2/319):
‘Ali ibn Abi Taalib (may Allaah have mercy on him) said: “The days of sacrifice are the Day of Sacrifice (yawm al-nahr) and the three days after it.” This is the view of the imam of the people of Basra, al-Hasan; the imam of the people of Makkah, ‘Ata’ ibn Abi Rabaah; the imam of the people of Syria, al-Awzaa’i; and the imam of the fuqaha’ of hadeeth, al-Shaafa’i (may Allaah have mercy on him). It was also the view favoured by Ibn al-Mundhir. The three days are specified because they are the days of Mina, the days of stoning (the Jamaraat) and the day of al-Tashreeq. It is forbidden to fast on these days. It was narrated via two isnaads, one of which supports the other, that the Prophet (peace and blessings of Allaah be upon him) said: “All of Mina is the place of sacrifice, and all the days of al-tashreeq are days of sacrifice.” End quote.
The hadeeth was classed as saheeh by al-Albaani in al-Silsilah al-Saheehah, 2476
Shaykh Ibn ‘Uthaymeen said in Ahkaam al-Udhiyah, concerning the time for offering the sacrifice:
It is from after the Eid prayer on the Day of Sacrifice until the sun sets on the last of the days of al-tashreeq, which is the thirteenth of Dhu’l-Hijjah. So there are four days of sacrifice: the day of Eid after the prayer, and three days after that. Whoever slaughters his sacrifice before the Eid prayer is over, or after the sun sets on the thirteenth, his sacrifice is not valid … but if he has an excuse for delaying it until after the days of al-tashreeq, such as if the animal ran away with no negligence on his part, and he did not find it until after the time was over, or if he delegated someone to do it on his behalf and his deputy forgot until the time was over, then there is nothing wrong with offering the sacrifice after the time has ended, because there is an excuse, by analogy with the fact that one who sleeps and misses a prayer or forgets it should offer the prayer as soon as he wakes up or remembers it.
It is permissible to offer the sacrifice during that time by night or by day, but it is better during the day, and the day of Eid after the two khutbahs is the best time. Each day is better than the following day, because that is hastening to do good. End quote.
It says in Fataawa al-Lajnah al-Daa’imah (11/406):
The days of sacrifice for pilgrims performing qiraan or tamattu’, and for offering the sacrifice (udhiyah) are four: the day of Eid and the three days after that. The time for sacrifice ends when the sun sets on the fourth day, according to the soundest scholarly opinion.
Shaykh Muhammad ibn ‘Uthaymeen (may Allaah have mercy on him) said: “Udhiyah is Sunnah mu’akkadah for the on who is able to do it, so a person should offer the sacrifice on behalf of himself and the members of his household.”
Fataawa Ibn ‘Uthaymeen, 2/661 [Definition of udhiyah and ruling thereon - IslamQA]
The person who scarify should be able to afford it's cost which has to be more than what he needs to spend on himself and his family. The prophet said:
"من كان له سَعة ولم يضح فلا يقربن مصلانا) رواه ابن ماجه ( 3123 ) وحسنه الألباني في " صحيح ابن ماجه)
(whoever is able to spend money and doesn't scarify, he should not come close to our masjid (mosque)) Narrated by Ibn Majjah and corrected by Al Albani in "Sahih Ibn Majah"
The Ruling on a Woman's Slaughter
It is permissible for a woman to slaughter an animal, the same as a man, as has been confirmed by the Sunnah from the Messenger of Allaah sallallaahu 'alaihi wa sallam. It is permissible to eat from the animal she has slaughtered, if she is a Muslim or one of the People of the Scripture and the animal was slaughtered according to the Islamic Law, even if a man was available to do it for her. It is not a condition for the permissibility of her sacrificial animal that there be no man present.
Shaykh `Abdul-`Azeez Bin Baz. Fatawa Islamiyah, Darussalam, vol 6, page 315
It is preferable (mustahabb) for the one who intends to sacrifice not to eat anything on that day before he eats from his sacrificial animal, if this is possible, because of the hadeeth: “Let every man eat from his sacrifice.” (Classed as saheeh in Saheeh al-Jaami’, 5349).
This eating should be after the Eid prayer and khutbah (sermon). This is the opinion of the scholars, including ‘Ali, Ibn ‘Abbaas, Maalik, al-Shaafa'i and others. The evidence for this is the hadeeth of Buraydah (may Allaah be pleased with him): “The Prophet (peace and blessings of Allaah be upon him) would not go out on the day of Fitr until he had eaten, and he would not eat on the day of Adhaa until he had slaughtered (his sacrifice).” (Al-Albaani said: its isnaad is saheeh. Al-Mishkaat, 1/452).
It is better for a person to slaughter the sacrifice himself, but if he does not, it is mustahabb for him to be present when it is slaughtered. It is mustahaab to divide the meat into three: one third to be eaten, one third to be given as gifts and one third to be given in charity. This was the opinion of Ibn Mas’ood and Ibn ‘Umar (may Allaah be pleased with them). The scholars agreed that it is not permissible to sell anything from its meat, fat or skin. In a saheeh hadeeth, the Prophet (peace and blessings of Allaah be upon him) said:
“Whoever sells the skin of his udhiyah, there is no udhiyah for him (i.e., it is not counted as udhiyah).”
(Classed as hasan in Saheeh al-Jaami’, 6118).
The butcher should not be given anything of it by way of reward or payment, because ‘Ali (may Allaah be pleased with him) said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) commanded me to take care of the sacrifice and to give its meat, skin and raiment (covering used for protection) in charity, and not to give anything of it to the butcher as a compensation. He said, ‘We will give him something from what we have.’” (Agreed upon).
It was said that it is permissible to give the butcher something as a gift, and that it is permissible to give some of it to a kaafir if he is poor or a relative or a neighbour, or in order to open his heart to Islam.
(Fataawa al-Shaykh ‘Abd al-‘Azeez ibn Baaz).
The Sunnah indicates that the one who wants to offer a sacrifice must refrain from taking anything from his hair, nails or skin from the first day of Dhu’l-Hijjah until he offers his sacrifice, because the Prophet (peace and blessings of Allaah be upon him) said: “When you see the new moon of Dhu’l-Hijjah, if any one of you wants to offer a sacrifice, let him not remove anything from his hair or nails until he has offered his sacrifice.”
According to another report: “Let him not touch any part of his hair or nails.” (Reported by Muslim with four isnaads, 13/146).
This command implies obligation and the prohibition implies that it is forbidden, according to the most correct opinion, because these are absolutes with no exceptions. If a person deliberately takes something (from his hair or nails), he must seek the forgiveness of Allaah, but he does not have to pay any fidyah (penalty), and his udhiyah is still valid. Whoever needs to remove some of his hair or nails because leaving it will cause him harm, such as a torn nail or a wound in a site covered by hair, should remove it, and there is no sin on him if he does so. This is not more serious than the muhrim (person in ihraam for Hajj or ‘Umrah) who is allowed to shave if not doing so will cause him harm. There is nothing wrong with men and women washing their hair during the first ten days of Dhu’l-Hijjah, because the Prophet (peace andblessings of Allaah be upon him) only forbade removing hair, and because the muhrim is allowed to wash his head.
The Wisdom behind the prohibition
The wisdom behind the prohibition on removing hair and nails is because the one who is going to offer a sacrifice is like the one who is in ihraam for Hajj and ‘Umrah with regard to some rituals, which is the offering of a sacrifice in order to draw closer to Allaah. Thus some of the rulings of ihraam apply to the one who wants to offer a sacrifice, so he should not touch his hair and nails until he has slaughtered his sacrifice, in the hope that Allaah will release him from the fire of Hell. And Allaah knows best.
If a person removes some of his hair and nails during the first ten days of Dhu’l-Hijjah because he is not planning to offer a sacrifice, then he decides to sacrifice, he should refrain from cutting his hair or nails from the moment he takes the decision.
There are some women who delegate their brothers or sons to do the sacrifice on their behalf so that they can cut their hair during the first ten days of Dhu’l-Hijjah. This is not correct, because the ruling applies to the one who is making the sacrifice, whether he or she delegates someone else to do the actual slaughter or not.
The prohibition does not apply to the person appointed, it applies to the person who wants to offer a sacrifice on behalf of himself, as is indicated by the hadeeth. As for the person who is doing the sacrifice on behalf of another, whether because of a will or because he has been delegated to do so, the prohibition does
not apply to him.
It is apparent that this prohibition applies to the one who is offering the sacrifice, and does not extend to his wife or children, unless one of them is offering a sacrifice on his or her own behalf. The Prophet (peace and blessings of Allaah be upon him) used to sacrifice on behalf of the family of Muhammad, and it was not reported that he forbade them to remove anything of their hair or nails.
Whoever is planning to offer a sacrifice, then decides to go for Hajj, should not remove anything of his hair or nails when he wants to enter ihraam, because this is Sunnah only when there is a need for it. But if he is doing Hajj “tamattu’” [where one performs ‘Umrah, then ends ihraam and enters a new state of ihraam for Hajj], he should shorten his hair when he finishes ‘Umrah because that is part of the ritual.
The things that are forbidden for the person who wants to offer a sacrifice are reported in the hadeeth quoted above. It is not forbidden for him to wear perfume or to have intercourse with his wife or to wear sewn garments and so on. And Allah knows best.
"Ruling of Udhyiah" by Muhammad Salih al-Munajjid