Musnad Abu Ya'la al-Mawsili 110:98

Muhammad ibn Abd al-Rahman ibn Sahm narrated to us, Abdullah ibn al-Mubarak narrated to us, Khalid al-Hadhdha’ narrated to us, from Ikrimah, from Ibn Abbas, who said: When the Messenger of Allah (ﷺ) would drink, he would say: "Start with the elder," or he said: "Start with the elders."