It was narrated that Jundub bin Sufyan said:
"I attended (the day of) sacrifice with the Messenger of Allah He led the people 9in prayer, then when he finished praying he saw some sheep that had been sacrificed. He said 'Whoever slaughtered (his sacrifice) before the prayer. Let him slaughtered (his sacrifice) before the prayer, let him slaughter a sheep in its place, and whoever has not slaughtered, let him offer a sacrifice in the name of Allah, the Mighty and Sublime."