عَنْ جُنْدَبِ بْنِ سُفْيَانَ، قَالَ شَهِدْتُ الأَضْحَى مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم فَلَمَّا قَضَى صَلاَتَهُ بِالنَّاسِ نَظَرَ إِلَى غَنَمٍ قَدْ ذُبِحَتْ فَقَالَ ‏ “‏ مَنْ ذَبَحَ قَبْلَ الصَّلاَةِ فَلْيَذْبَحْ شَاةً مَكَانَهَا وَمَنْ لَمْ يَكُنْ ذَبَحَ فَلْيَذْبَحْ عَلَى اسْمِ اللَّهِ ‏

Jundab b. Sufyan (RA) reported: I was with Allah’s Messenger (ﷺ) (on the occasion) of ‘Id al-Adha. After he had completed the prayer with people, he found that the goats had been slaughtered, whereupon he said: He who slaughtered his sacrificial animal before the prayer should slaughter a goat (again) in its stead and he who has not slaughtered he should slaughter it by reciting the name of Allah. [Sahih Muslim 1960]

عَنِ الْبَرَاءِ، قَالَ ضَحَّى خَالِي أَبُو بُرْدَةَ قَبْلَ الصَّلاَةِ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏”‏ تِلْكَ شَاةُ لَحْمٍ ‏”‏ ‏.‏ فَقَالَ يَا رَسُولَ اللَّهِ إِنَّ عِنْدِي جَذَعَةً مِنَ الْمَعْزِ فَقَالَ ‏”‏ ضَحِّ بِهَا وَلاَ تَصْلُحُ لِغَيْرِكَ ‏”‏ ‏.‏ ثُمَّ قَالَ ‏”‏ مَنْ ضَحَّى قَبْلَ الصَّلاَةِ فَإِنَّمَا ذَبَحَ لِنَفْسِهِ وَمَنْ ذَبَحَ بَعْدَ الصَّلاَةِ فَقَدْ تَمَّ نُسُكُهُ وَأَصَابَ سُنَّةَ الْمُسْلِمِينَ ‏”‏

Al-Bara’ (RA) reported: My maternal uncle Abu Burda sacrificed his animal before (‘Id) prayer. Thereupon Allah’s Messenger (ﷺ) said: That is a goat (slaughtered for the sake of) flesh (and not as a sacrifice on the day of Adha). My uncle said: I have a lamb of six months. Thereupon he ﷺ said: Offer it as a sacrifice, but it will not justify for anyone except you, and then He ﷺ said: He who sacrificed (the animal) before (‘Id) prayer, he in fact slaughtered it for his own self, and he who slaughtered after prayer, his ritual of sacrifice became complete and he in fact observed the religious practice of the Muslims. [Sahih Muslim 1961]

The time for Qurbani begins after the Eid Salaah on the 10th of Zul Hijjah and ends at the setting of the sun on the 12th of Zul Hijjah.

It is better to make Qurbani on the first day, then the second, and thereafter the third.

If the Qurbani has been offered before the Eid Salaah, it will have to be repeated.

In rural and village areas where Jumu’ah and Eid Salaah are not performed, Qurbani may be performed as soon as Fajr (Subhus Saadiq) sets in on the 10th of Zul Hijjah. (Fatawa Hindiyyah)

If a person residing in a town (where Eid salaah is performed) arranges for his animal to be slaughtered in a village (where Eid Salaah is not performed), then it is permissible for his animal to be slaughtered before he performs his Eid Salaah. (Fataawa Shaamiyyah)

It is preferable to slaughter during the day. (Fatawa Hindiyyah)