Musnad Abu Ya'la al-Mawsili 111:132

Zuhayr narrated to us, Rawh ibn ‘Ubadah narrated to us, Ibn Jurayj narrated to us, he said: Zakariyya ibn ‘Umar narrated to me that ‘Ata’ informed him that ‘Abdullah ibn ‘Abbas invited al-Fadl ibn ‘Abbas on the day of ‘Arafah to food. He said: "I am fasting." ‘Abdullah said: "Do not fast, for the Prophet, peace and blessings of Allah be upon him, had a vessel containing milk brought near to him, and he drank from it on this day, and the people follow your example."