Qurbani during Eid-ul Adha is an act to commemorate Prophet Ibrahim’s sacrifice as mentioned in the Quraan.

And, when he (his son) was old enough to walk with him, he said: "O my son! I have seen in a dream that I am slaughtering you (offer you in sacrifice to Allah), so look what you think!" He said: "O my father! Do that which you are commanded, Insha' Allah (if Allah will), you shall find me of As-Sabirin (the patient ones, etc.)." Then, when they had both submitted themselves (to the Will of Allah), and he had laid him prostrate on his forehead. And We called out to him: "O Abraham! You have fulfilled the dream (vision)!" Verily! Thus do We reward the Muhsinun (good-doers).Verily, that indeed was a manifest trial. And We ransomed him with a great sacrifice (i.e. a ram). And We left for him (a goodly remembrance) among generations (to come) in later times. (Sura Saffat, verses 102-108.)

Prophet Muhammad (PBUH) taught Muslims the way of remembering the act of Ibrahim. He stayed 10 years in Madina and performed sacrifice at Eid-ul-Adha. (Tirmidhi)

Qurbani in Islamic terms means the slaughtering of an animal with the intention of getting close to Allah (SWT) by giving some or all of the meat to the poor and destitute. Animals that can be sacrificed are goats, cows and camels. They are sacrificed on the day of Eid-ul-Adha and also on the three days after (the 11, 12 and 13th of Dhulhijjah).

Benefits of Qurbani

Doing charity to the poor by contributing and distributing the meat to them and the destitute. These acts would spread happiness and cheers amongst them especially during the festival of Eid-ul-Adha where Muslims are in the spirit of festivities.  

Who should give Qurbani

Person who possesses Nisab (zakatable asset) should give Qurbani.  It is not obligatory (fard) but is highly recommended (wajib)*, according to the Hanafi school of thought. However, Qurbani is a Sunnah act according to the Shafi, Hanbali, Maliki, and Jafari schools of thought.

Requirements of Qurbani

The animals to be slaughtered must be a goat, sheep, cattle (cow, ox, water buffalo), or camel. Goats and sheep have to be at least one year old.For cows the age must be at least two years old. Camels must be at least five years old. Goats and sheep count as one share per animal. Cattle and camels count as seven shares per animal.

They must be free from any form of handicap such as blind, sick, limp and undernourished. It also must be free of any defects such as a cut-off ear, tail, broken teeth,or broken horn. However, the goat/sheep can be used if only a few teeth are broken and most teeth are still intact. In addition, if its horn is broken midway and not from the root, it is persmissible to use such an animal. Injuries sustained during the qurbani do not invalidate the qurbani.

The animals must be slaughtered in the appropriate humane ways. It has to be done by a Muslim adhering to the Islamic way of slaughtering the animal.  

Time of Qurbani

The time for Qurbani starts from sunrise after the performance of the Eidul Adha prayers which falls on the 10th of Zhulhijjah till the sunsets on the 12th of Zhulhijjah. The best time is to perform the acts of Qurbani immediately after the completion of the Eid-ul-Adha prayers.

It was reported that the Prophet Muhammad (PBUH) said:
The first thing that we do on the day of Eid is to perform the prayers. Then we go home and carry out our Qurbani.Thus whoever does those acts has conformed to our sunnah. And for those who slaughtered  before it, then the meat is for the family members and not as an act of Qurbani. (Sahih Al-Bukhari Volume 2, Book 15, Number 82)

Distribution of the Qurbani meat
It is preferable that the meat from Qurbani be divided in three equal parts: one for the home, one for relatives and friends, and one for the poor and needy. The meat from qurbani can be distributed to the poor, rich, Muslim or non-Muslim.  

*Wajib, in the Hanafi school, is an obligation which is almost Fard, except that there is some (margin of uncertainty, which may occur in the form of counter-evidence, which suggests non-obligatory nature of the deed), and the scholars have therefore refrained from pronouncing a decisive verdict of "fard" on it. Nevertheless, for purposes of action, a wajib is treated like a fard, in that it should not be deliberately discarded, and it must be made up if it was missed for some reason. For this reason, 'wajib' of the Hanafi school is also known as "fard `amali" (i.e. an 'action fard') as opposed to fard i`tiqadi ('belief fard'), the normal fard, which one is required not only to act upon, but also to believe with full certainty and conviction that it is without doubt a duty.