(Imām Bukhārī narrates): Abu Nu'aim narrated to us, he said: Muhammad bin Talhah narrated to us from Zubaid from al-Sha'bi from al-Bara, may Allāh be pleased with him, he relates that

the Prophet ﷺ went towards al-Baqi on the day of Eid al-Adha, so he prayed two rak'ahs, then he turned his face towards us and said: The first act of worship for us on this day of ours is that we begin with the prayer, then we return, so we perform the nahr (sacrifice). So whoever does this has followed our Sunnah, and whoever slaughtered before this, then that is only something which he prepared quickly for his family, and it is not anything from the sacrifice. Then a man stood up and said: O Messenger of Allāh! I have already slaughtered, and I have a goat, six months old, which is more fattened than a one-year-old goat. He said: Slaughter it, and after you it will not suffice for anyone else.