Musnad Abu Ya'la al-Mawsili 42:126

Ibrahim al-Sami narrated to us, Yahya bin Maymun narrated to us, Ali bin Zayd narrated to us, from Abu Nadra, from Abu Sa’id, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said to Ibn Abbas: "O boy, O little boy," or "O little boy, O boy, preserve some words for me." Then he mentioned the hadith in the Mu'jam.