Sahih Muslim Book 22, Hadith Number 4865.

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.

Thauban, the freed slave of Allah’s Messenger (may peace be upon him), reported: Allah’s Messenger (may peace be upon him) said to me on the occasion of Hajjat-al-Wada’ (the Farewell Pilgrimage): Make the flesh usable. So I made it usable (for him) and he ate it constantly until he reached Medina. This hadith has been narrated on the authority of Yabya b. Hamza with the same chain of transmitters, but he did not say: On the occasion of Hajjat-al-Wada’.