Musnad Ahmad 2:278

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Salamah ibn Kuhayl, he said: I heard Abu al-Hakam say: I asked Ibn 'Umar about the *jar* (earthenware jar), and he narrated to us from 'Umar: That the Messenger of Allah (peace and blessings of Allah be upon him) forbade the *jar*, the *duba'* (gourd), and the *muzaffat* (pitch-coated vessel).