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 will not do 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, has to do with 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 a Muslim from Abu Hurayrah (may Allaah be pleased with him), who said that 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.