Whoever slaughters his sacrifice before the 'Eid prayer should repeat it Sahih al-Bukhari 5563
Arabic hadith text
حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ فِرَاسٍ، عَنْ عَامِرٍ، عَنِ الْبَرَاءِ، قَالَ صَلَّى رَسُولُ اللَّهِ صلى الله عليه وسلم ذَاتَ يَوْمٍ، فَقَالَ "مَنْ صَلَّى صَلاَتَنَا وَاسْتَقْبَلَ قِبْلَتَنَا، فَلاَ يَذْبَحْ حَتَّى يَنْصَرِفَ ". فَقَامَ أَبُو بُرْدَةَ بْنُ نِيَارٍ فَقَالَ يَا رَسُولَ اللَّهِ فَعَلْتُ. فَقَالَ " هُوَ شَىْءٌ عَجَّلْتَهُ ". قَالَ فَإِنَّ عِنْدِي جَذَعَةً هِيَ خَيْرٌ مِنْ مُسِنَّتَيْنِ آذْبَحُهَا قَالَ " نَعَمْ، ثُمَّ لاَ تَجْزِي عَنْ أَحَدٍ بَعْدَكَ ". قَالَ عَامِرٌ هِيَ خَيْرُ نَسِيكَتِهِ
Translation
Narrated Al-Bara'
One day Allah's Messenger (ﷺ) offered the `Id prayer and said, "Whoever offers our prayer and faces our Qibla should not slaughter the sacrifice till he finishes the `Id prayer." Abu Burda bin Niyar got up and said, "O Allah's Messenger (ﷺ)! I have already done it. The Prophet (ﷺ) said, "That is something you have done before its due time." Abu Burda said, "I have a Jadha'a which is better than two old sheep; shall I slaughter it?" The Prophet (ﷺ) said, "Yes, but it will not be sufficient for anyone after you."