Sahih Muslim Book 22, Hadith Number 4855.

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 ‘Umar reported that Allah’s Messenger (may peace be upon him) forbade that the flesh of sacrificial animals be eaten beyond three (days) Salim (son of Ibn Umar) said: Ibn ‘Umar did not eat the flesh of the sacrificial animals beyond three (days). Ibn Abu ‘Umar said: “Beyond three days.”