Sahih Muslim Book 22, Hadith Number 4867.

Chapter : It was not permissible to eat the flesh of sacrificial animals beyond three days at the beginning of Islam, but this prohibition was abrogated, and now it is permissible.

Ibn Buraida, on the authority of his father, reported Allah’s Messenger (may peace be upon him) having said this: I used to forbid you. The rest of the hadith is the same.