"Abu Hurairah narrated that people among the Companions of the Prophet (S.A.W) would say:
"Truffles are the earth's smallpox." So the Messenger of Allah (S.A.W) said: "Truffles are a form of manna, and its liquid is a cure for the eye. Al-'Ajwah is from Paradise, and it contains a cure for poison." (FR)
English reference (FR): Vol. 4, Book 2, Hadith 2068 (FR)
Arabic reference (FR): Book 28, Hadith 2210 (FR)