Musnad Ahmad 947:9

Abu al-Nadr narrated to us, Abd al-Rahman—meaning Ibn Abd Allah ibn Dinar—narrated to us, from Zayd ibn Aslam, from Ata ibn Yasar, from Abu Waqid al-Laythi, who said: When the Messenger of Allah (peace and blessings of Allah be upon him) arrived in Medina, the people were cutting the humps of camels and cutting the fat-tails of sheep. The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whatever is cut from an animal while it is alive, it is carrion."