It wasnarrated from Aswad bin Qais that he heard Jundub Al-Bajalisay:
"Iwas present on Adha day with the Messenger of Allah (ﷺ), andsomepeople slaughtered before the prayer. The Prophet (ﷺ) said:'Whoever among you has slaughtered before the prayer, let himrepeathis sacrifice, and whoever has not, let him offer hissacrifice in theName of Allah.'"
English reference: Vol. 4, Book 26, Hadith 3152
Arabic reference: Book 26, Hadith 3272