The Book of Sacrifices
35/5. Chapter:
The prohibition of eating sacrificial meat for more than three days, which applied at the beginning of Islam but was then abrogated, and now it is permissible to eat it as long as one wants.
Sahih Muslim
حَدَّثَنِي حَرْمَلَةُ بْنُ يَحْيَى، أَخْبَرَنَا ابْنُ وَهْبٍ، حَدَّثَنِي يُونُسُ، عَنِ ابْنِ شِهَابٍ، حَدَّثَنِي أَبُو عُبَيْدٍ، مَوْلَى ابْنِ أَزْهَرَ أَنَّهُ شَهِدَ الْعِيدَ مَعَ عُمَرَ بْنِ الْخَطَّابِ قَالَ ثُمَّ صَلَّيْتُ مَعَ عَلِيِّ بْنِ أَبِي طَالِبٍ - قَالَ - فَصَلَّى لَنَا قَبْلَ الْخُطْبَةِ ثُمَّ خَطَبَ النَّاسَ فَقَالَ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَدْ نَهَاكُمْ أَنْ تَأْكُلُوا لُحُومَ نُسُكِكُمْ فَوْقَ ثَلاَثِ لَيَالٍ فَلاَ تَأْكُلُوا .
Abu 'Ubaid, the freed slave of Ibn Azhar, reported that he said 'Id (prayer) with Umar b. al-Khattab, and then said the 'Id (prayer) with 'Ali b. Abu Talib. He (the narrator further) reported: He led us in prayer before delivering the sermon and then addressed the people saying: Allah's Messenger (ﷺ) has forbidden you to eat the flesh of your sacrificial animals beyond three nights, so do not eat that.
Reference : Sahih Muslim 1969bIn-book reference : Book 35, Hadith 35USC-MSA web (English) reference : Book 22, Hadith 4851