Musnad Ahmad 5:669

Yazid narrated to us, Hammad ibn Salamah informed us, from Ali ibn Zayd, from Rabi’ah ibn al-Nabighah, from his father, from Ali: "That the Messenger of Allah (peace and blessings of Allah be upon him) forbade visiting graves, and [the use of] vessels, and that the meat of the sacrificial animals be kept after three [days]." Then he said: "I had forbidden you from visiting graves, so visit them, for they remind you of the Hereafter. And I had forbidden you from [the use of] vessels, so drink from them, but avoid everything that intoxicates. And I had forbidden you from keeping the meat of the sacrificial animals after three [days], so keep [it] as much as seems good to you."