Musnad Abu Ya'la al-Mawsili 51:15

Abu Sa'id al-Qawariri narrated to us, 'Abd al-Warith bin Sa'id narrated to us, from 'Ata' bin al-Sa'ib, from 'Amr bin Hurayth, who said: The Messenger of Allah (peace be upon him) said: "The truffle is of the manna, and its water is a cure for the eye."