Musnad Ahmad 947:8

'Abd al-Samad and Hammad ibn Khalid—the meaning being the same—said: 'Abd al-Rahman ibn 'Abd Allah ibn Dinar narrated to us. 'Abd al-Samad said in his narration: Zayd ibn Aslam narrated to us, from 'Ata' ibn Yasar, from Abu Waqid al-Laythi, who said: The Messenger of Allah (peace and blessings of Allah be upon him) arrived in Medina, and there were people there who would go to the fat-tails of sheep and the humps of camels and cut them off. 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."