Sayyiduna al-Irbad bin Sariyah (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) was asked about the slaughtered animals of the Christians, their churches and their festivals, and he said: "If you do not eat it, then feed it to me."
Al-Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains Abu Bakr bin Abi Maryam, who is da'if (weak).