(28) باب فَضْلِ الْكَمْأَةِ وَمُدَاوَاةِ الْعَيْنِ بِهَا
Sa'id b. Zaid b. 'Amr b. 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 Israil, and its juice is a medicine for the eyes.
Reference: Sahih Muslim 2049 d
In-book reference: Book 36, Hadith 219
USC-MSA web (English) reference(deprecated numbering scheme): Book 23, Hadith 5086