Amr bin Hurayth narrates from his father, Sayyiduna Hurayth (may Allah be pleased with him), that the Messenger of Allah (peace and blessings be upon him) said: "Truffles are from the manna, and their water is a cure for the eye."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 3457