Narrated Al-Bara':

I heard the Prophet (ﷺ) delivering a sermon, and he said (on the Day of `Id-Allah. a), "The first thing we will do on this day of ours is that we will offer the `Id prayer, then we will return and slaughter our sacrifices; and whoever does so, then indeed he has followed our tradition, and whoever slaughtered his sacrifice (before the prayer), what he offered was just meat that he presented to his family, and that was not a sacrifice." Abu Burda got up and said, "O Allah's Messenger (ﷺ)! I slaughtered the sacrifice before the prayer and I have got a Jadha'a which is better than an old sheep." The Prophet (ﷺ) said, "Slaughter it to make up for that, but it will not be sufficient for anybody else after you."