Musnad Ahmad 215:2

'Abd al-Samad narrated to us, Hisham and Hammam narrated to us, from Qatadah, from al-Hasan, from Jun ibn Qatadah, from Salamah ibn al-Muhabbaq, that the Messenger of Allah (may Allah bless him and grant him peace) passed by a house with a water skin hanging in its courtyard, so he asked for a drink. It was said: "It is dead (i.e., made from the hide of an animal that died without slaughter)." He said: "The tanning of the hide is its slaughter."