Sayyiduna Jundub (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, and he (peace and blessings be upon him) came to know that some people had slaughtered before the prayer. So he (peace and blessings be upon him) addressed the people and said: "Whoever slaughtered before the prayer, let him slaughter again; and whoever has not, let him slaughter with the name of Allah."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 1704