I heard the Prophet ﷺ say, "Truffles are a form of manna, and their juice is a cure for the eye."
سمعت النبي ﷺ يقول: الكمأة من المن، وماؤها شفاء للعين.
Bukhari narrated it in tafsir (4639), and Muslim in drinks (158:2049), both of them through Shubah, from Abdul-Malik bin Umayr, who said, I heard Amr bin Hurayth say, I heard Saeed bin Zayd say, then he related it. Their wording is the same.