Jundub bin Sufian (RAA) narrated, 'I witnessed (the prayer of) 'Idul Ad-ha with the Messenger of Allah (ﷺ) and when he finished his prayer with the people, he looked at a sheep which had been sacrificed, so he said, "Anyone who has sacrificed before the prayer must sacrifice another goat instead (of the one which he slaughtered before the prayer) and if anyone has not sacrificed he should do so in Allah's name." Agreed upon.
English reference: Book 12, Hadith 1390
Arabic reference: Book 12, Hadith 1349