Musnad Ahmad 5:614

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Sulayman, from Ibrahim al-Taymi, from al-Harith ibn Suwayd, from Ali: "That the Messenger of Allah, peace and blessings of Allah be upon him, forbade the *duba'* (gourd) and the *muzaffat* (pitch-coated vessel)."