The first point that we have to understand is that Qurbani(Udhiyah) is prescribed at a particular time just like salah/prayer is at a prescribed time. Fasting is prescribed in Ramadan. Hajj is prescribed at a specific time. Udhiyah is an act of worship that has a start and an end time.
The Prophet (ﷺ) said, إِنَّ أَوَّلَ مَا نَبْدَأُ مِنْ يَوْمِنَا هَذَا أَنْ نُصَلِّيَ، ثُمَّ نَرْجِعَ فَنَنْحَرَ، فَمَنْ فَعَلَ فَقَدْ أَصَابَ سُنَّتَنَا ”.
He said that “the first thing we do on this day is we pray, i.e. the prayer of Eid and then we return back then we perform our slaughter or sacrifice and whoever has done so, then they have followed my sunnah”.
And so, performing the Udhiyah begins at the time after the prayer of Eid has taken place and the Prophet (ﷺ) said specifically: “whoever does it beforehand, it’s not accepted.”
وَمَنْ ذَبَحَ قَبْلَ
Whoever has done their slaughter before this time,
فَإِنَّمَا هُوَ لَحْمٌ عَجَّلَهُ لأَهْلِهِ
All he has done is given his family meat and he does not have anything of the النُّسُكِ .
He does not have any part of the actual ritual, the reward of doing the Udhiyah and the Qurbani. So, it begins at the time after the prayer has been performed and the scholars say the best time is after the khutbah. So, the prayer, then the Khutbah then the time for slaughter begins.
When is the end of this time period?
Here, there is some difference of opinion. Some scholars say it is the fourth day after Eid, so the 13th. So, you have the 10th, the 11th, and 12th, and the maghrib of the 13th is the end point.
But the more popular opinion amongst Mazahib and the scholars is that it ends at the end of the 12th. So, you have only 3 days — the day of Eid and two days after it and the end — the maghrib of the 12th — is when the cutoff point comes. Therefore, it is preferable for people to finish their Udhiyah, to finish their sacrifice before the end of the 12th so it is valid according to all of the opinions. So, after the prayer and after the Khutbah, this is the best time to sacrifice. The scholars also say that it is great to sacrifice in the morning rather than at night. Although it is permissible to sacrifice at night, the word Udhiyah comes from the word doha which is the forenoon and so, the morning time is better. People see that the rituals of Allah are taking place. Those who are Masakin, they can see and they will be able to participate in this festivity and in this ritual as well. So, it is preferable and insha’Allah better and considered for us to do it earlier. The more we delay, it is discouraged but if somebody needed to delay the 2nd day or the 3rd day, insha’Allah, there is no problem.