Sa'id bin Zaid (May Allah be pleased with him) reported:
I heard the Messenger of Allah (ﷺ) saying, "Truffle (edible fungus) is a species of Al-Manna and their water cures eye diseases."[Al-Bukhari and Muslim]
App reference: Book 19, Hadith 61
Arabic/English book reference: Book 19, Hadith 1868