He who slaughtered the animal before prayer should slaughter (another animal as a sacrifice). The rest of the hadith is the same.
Sahih Muslim Book 35, Hadith 17
← Previous Hadith
He who slaughtered (the animal as a sacrifice) before the ('Id) prayer. should repeat it (i. e. offer another animal). Thereupon a person stood up and said: Messenger of Allah, that is the day when meat is much desired, and he also made a mention of the need of his neighbour, and perhaps Allah's Messenger (ﷺ) attested it. He (the person who had sacrificed the animal before the 'Id prayer) said: I have a goat of less than one year of age with me and I like it more than two fleshy goats; should I offer it as a sacrifice? He permitted him to do so. He (the narrator) said: I do not know whether this permission was granted to anyone else besides him or not. Allah's Messenger (ﷺ) then turned towards two rams. and he slaughtered them, and the people' came to the goats and got them distributed amongst themselves (for offering them as sacrifice).
Sahih Muslim Book 35, Hadith 16 Next Hadith → Allah's Messenger (ﷺ) addressed us on the day of 'Id al-Adha. He smelt the odour of flesh and he prohibited thern from slaughtering (the animals before the 'Id prayer), saying: He who slaughtered the animals (before the 'Id prayer) should do that again (as it is not valid as a sacrifice).
Sahih Muslim Book 35, Hadith 18
Sahih Muslim Book 35, Hadith 16 Next Hadith → Allah's Messenger (ﷺ) addressed us on the day of 'Id al-Adha. He smelt the odour of flesh and he prohibited thern from slaughtering (the animals before the 'Id prayer), saying: He who slaughtered the animals (before the 'Id prayer) should do that again (as it is not valid as a sacrifice).
Sahih Muslim Book 35, Hadith 18