Al-Aswad bin Qays narrates that Sayyiduna Jundub bin Sufyan (may Allah be pleased with him) said: I was present with the Messenger of Allah (peace and blessings be upon him) on the day of Eid al-Adha. He led the people in prayer, and when the Messenger of Allah (peace and blessings be upon him) finished the prayer, he saw that goats had already been slaughtered. So he said: "Whoever slaughtered before the prayer, let him slaughter a goat in its place; and whoever has not slaughtered, let him slaughter with the name of Allah."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 1702