Narrated Sa`id bin Zaid:
Allah's Messenger (ﷺ) said, "The Kam'a (i.e. a kind of edible fungus) is like the Manna (in that it is obtained without effort) and its water is a (medicine) cure for eye trouble."
USC-MSA web (English) reference: Vol. 6, Book 60, Hadith 5
Arabic reference: Book 65, Hadith 4478