Musnad Ahmad 31:850

Rawh narrated to us, Ash'ath narrated to us, from al-Hasan, from Abu Sa'id al-Khudri, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) forbade the *duba* (gourd), the *hantam* (green glazed jar), the *naqir* (hollowed-out log), and the *muzaffat* (pitch-coated vessel). And he forbade mixing raisins and dates, or unripe dates (*busr*) and ripe dates (*tamr*)."