Sa'id bin Zaid bin 'Amr bin Nufail reported Allah's Messenger (ﷺ) as saying: Truffles are a kind of 'Manna' which Allah the Glorious and Exalted, sent down upon the people of Israel, and its juice is a medicine for the eyes.
Hadith ReferenceSahih Muslim / The Book of Drinks / Hadith: 2049