Musnad Ahmad 658:66

Isma'il narrated to us, Dawud informed us, from al-Sha'bi, from al-Bara' ibn 'Azib, who said: The Messenger of Allah (peace and blessings of Allah be upon him) delivered a sermon to us on the day of sacrifice and said: "Let no one slaughter until we have prayed." My maternal uncle stood up and said: "O Messenger of Allah, this is a day in which meat is disliked, and I have hastened, and I have slaughtered my sacrifice to feed my family and the people of my house, or my family and my neighbors." He said: "You have done so, so repeat the slaughter with another." He said: "O Messenger of Allah, I have a young she-goat (anaq) that is better than two meat-sheep; shall I slaughter it?" He said: "Yes, and it is better than your two sacrifices, but a six-month-old lamb (jadha'ah) shall not suffice for anyone after you."