Musnad Abu Ya'la al-Mawsili 65:14

Khalaf ibn Hisham narrated to us, Abu 'Awanah narrated to us, from al-Aswad ibn Qays, from Jundub ibn Sufyan, who said: We prayed with the Prophet, may Allah bless him and grant him peace, one day, and some people slaughtered their sacrificial animals before the prayer. When the Messenger of Allah, may Allah bless him and grant him peace, turned away and saw that they had slaughtered before the prayer, he said: "Whoever slaughtered his sacrificial animal before the prayer, let him slaughter another one in its place. And whoever has not yet slaughtered until we prayed, let him slaughter in the name of Allah."