Sahih Muslim | Book 23 | Hadith Number 5084
Narrated by Sa'id b. Zaid b. 'Amr b. Nufail
Sa'id b. Zaid b. 'Amr b. Nufail reported: I heard Allah's Apostle (may peace be upon him) as saying: Truffles are a kind of 'Manna' and their juice is a medicine for the eyes.