Musnad Abu Ya'la al-Mawsili 42:343

Zuhayr narrated to us, Affan narrated to us, Hammad narrated to us, from Ali bin Zayd, from Abu Nadra, from Abu Sa’id al-Khudri, that the Messenger of Allah (peace and blessings of Allah be upon him) said to Ibn Sayyad: "What do you see?" He said: "I see a throne upon the sea, surrounded by snakes." The Messenger of Allah (peace and blessings of Allah be upon him) said: "That is the throne of Iblis."