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 عَبْدُ الْجَبَّارِ بْنُ الْعَلاَءِ، حَدَّثَنَا سُفْيَانُ، حَدَّثَنَا الزُّهْرِيُّ، عَنْ أَبِي عُبَيْدٍ، قَالَ شَهِدْتُ الْعِيدَ مَعَ عَلِيِّ بْنِ أَبِي طَالِبٍ فَبَدَأَ بِالصَّلاَةِ قَبْلَ الْخُطْبَةِ وَقَالَ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم نَهَانَا أَنْ نَأْكُلَ مِنْ لُحُومِ نُسُكِنَا بَعْدَ ثَلاَثٍ .
Abu Ubaid reported: I was with 'Ali b. Abi Talib on the occasion of the 'Id day. He started with the 'Id prayer before delivering the sermon, and said: Allah's Messenger (ﷺ) forbade us to eat the flesh of our sacrificial animals beyond three days.
Reference : Sahih Muslim 1969aIn-book reference : Book 35, Hadith 34USC-MSA web (English) reference : Book 22, Hadith 4850