Sahih Muslim

I was with Allah's Messenger (ﷺ) on the day of 'Id al-Adha. While he had not returned after having offered (the Id prayer) and finished it, he saw the flesh of the sacrificial animals which had been slaughtered before he had completed the prayer. Thereupon he (the Holy Prophet) said: One who slaughtered his sacrificial animal before his prayer or our prayer ('Id), he should slaughter another one in its stead, and he who did not slaughter, he should slaughter by reciting the name of Allah.

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 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.

This hadith has been narrated on the authority of al-Aswad b. Qais with the same chain of transmitters.

I saw Allah's Messenger (ﷺ) observing ('Id) prayer on the Day of Sacrifice (10th of Dhu'l-Hijja) and then delivering a sermon and he said: He who sacrificed the (animal) before offering ('Id) prayer, he should offer again in its stead, and he who did not sacrifice the animal should slaughter it by reciting the name of Allah.

This hadith has been narrated on the authority of Shu'ba through another chain of transmitters.

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). He said: I have a lamb of six months. Thereupon he said: Offer it as a sacrifice, but it will not justify for anyone except you, and then 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.

Apostle of Allah, it is the day of meat and it is not desirable (to have longing for it and not to make use of it immediately), so I hastened in offering my animal as a sacrifice, so that I might feed my family and neighbours and my kith and kin. Thereupon Allah's Messenger (ﷺ) said: Offer again your sacrifice. He said: Messenger of Allah, I have a small milch goat of less than one year, and that is better than two dry goats (from which only) meat (can be acquired). Thereupon he said: That is better than the two animals of sacrifice on your behalf, and the sacrifice of a goat, of less than six months shall not be accepted as a sacrifice on behalf of anyone after your (sacrifice).

Allah's Messenger (ﷺ) delivered an address on the day (of Nahr) in which he said: None of you should offer sacrifice of animals until he has completed the ('Id) prayer. Thereupon my maternal uncle said: Messenger of Allah, it is the day of meat, so it is not desirable (to keep my family in the state of longing). The rest of the hadith is the same.

He who observes prayer like our prayer and turns his face towards our Qibla (in prayer) and who offers sacrifices (of animals) as we do, he must not slaughter the (animal as a sacrifice) until he has completed the prayer. Thereupon my maternal uncle said: Messenger of Allah, I have sacrificed the animal on behalf of my son. The Messenger of Allah (ﷺ) said: This is the thing in which you have made haste for your family. He said: I have a goat with me better than two goats. Thereupon he said: Sacrifice it for that is the best.