Definition of Udhiya
The Udhiyah refers to the sacrificial animal (camel, cattle, sheep or goat) that is sacrificed as an act of worship to Allaah, during the period from after the Eid prayer on the Day of Nahr (Eid al-Adha) until the last day of Tashreeq (the 13th day of Dhul-Hijjah), with the intention of offering sacrifice .
The Udhiyah is Sunnah mu’akkadah (highly recommended) for the one who is able to do it, according to the majority of scholars . Anas ibn Maalik said: “The Prophet sacrificed two white rams speckled with black. He slaughtered them with his own hand, said ‘Allaahu akbar’ and put his foot on their necks.” [Saheeh al-Bukhaari (5558) and Saheeh Muslim (1966)]
Required Age 
|six months for a lamb||one year for a goat|
|two years for a cow that can be shared by seven people||five years for a camel that can be shared by seven people|
Conditions of an Udhiyah
The animal that has reached the required age should be completely free of any faults . The Prophet was asked about what types of animals one should avoid when sacrificing. He gestured with his hand and said: “They are four: The lame animal that clearly limps or walks crookedly; the one-eyed animal that has obviously lost the sight of one eye; the sick animal that clearly has signs of illness; and the emaciated animal (or a broken leg) with no marrow.” Reported by Maalik, [Al-Muwatta: Book of Sacrificial Offerings (1)]
Timing for Sacrifice
The Udhiyah can be sacrificed after the Eid prayer till before the sunset of the last day of Tashreeq, which is 13th Dhul-Hijjah .
General Rulings 
1-It is from the Sunnah that one includes his household in his Udhiyah. So, when he slaughters his sheep, he should say, ” Bismillah Allaahu-Akbar. Allaahumma haatha ‘annee wa ‘an ahli baytee” meaning “In the name of Allah. Allaah is the greater. O Allah! This is on my behalf and on behalf of my family members.”
2-It is not permissible to sell anything from the Udhiyah‘s meat, skin or fat. Also, the butcher must not be given anything from the sacrifice, as a way of reward or payment.
3-Slaughtering the Udhiyah with one’s own hands is better, but if one does not do so, it is Mustahabb (liked, preferable) for him to be present at the time of slaughtering.
4-Eating from one’s sacrifice is Mustahabb. It is also Mustahabb for him, who performs an Udhiyah, not to eat before he offers his sacrifice; he should break his fast with the meat of his sacrifice the prayer.
5-Umm Salamah related that the Prophet said: “If you see the Hilaal (new moon) of Dhul-Hijjah, and any one of you wants to make a sacrifice, then he should not cut (anything) from his hair and his nails.” and in one narration he said: “…then he should not take (cut) anything from his hair, nor from his nails, until he sacrifices.” [Saheeh Muslim]
6- Dividing the meat into three is Mustahabb, one-third to keep for oneself, one-third to be given as gifts and one-third to be given in charity.
 Abdulmajeed Hassan, Udhiya-Sacrifice, As-Sunna issue no: 01,
 Dr. Wahba Zuhail, Al-Wajeez fi Al-Fiqah Al-Islami, Dar Alfikir, Damascus, Vol 1, ed 2 11427 H – 2007
 Muhammed Al-Alawi, Fiqah Al-Udhiya, Dar Majid, Jidda, Shawwal 1419 H.
 Saheeh al-Bukhaari
 Saheeh Muslim
 Al-Muwattaa by Imam Malik