The Messenger of Allah ﷺ came out to them while they were discussing truffles, with some of them calling them "the smallpox of the earth." The Prophet ﷺ said, "Truffles are from the manna, and their juice is a cure for the eye. The ajwa date is from Paradise, and it is a cure for poison."
حدثنا روح حدثنا سعيد عن قتادة عن شهر بن حوشب عن عبد الرحمن بن غنم
أن رسول الله ﷺ خرج عليهم وهم يذكرون الكمأة وبعضهم يقول جدري الأرض فقال النبي ﷺ الكمأة من المن وماؤها شفاء للعين والعجوة من الجنة وهي شفاء من السم
Bukhari and Muslim, along with Tirmidhi, narrated it from Abu Hurairah, and its chain is sahih. Ibn Majah narrated it in the Book of Medicine from Muhammad bin Bashshar Bundar.As for what relates to the text of the hadith, Abu Hurairah, may Allah be pleased with him, tested this property found in truffles and found it to be sound, as others tested it after him as well. Imam Nawawi related that one of the scholars of his time lost his eyesight, and when he applied truffle water as eye kohl, he was healed by Allah's permission.Truffles are a plant with no leaves and no stem, found in the ground without being cultivated. It is said they were named this because of their hidden nature, and one says "kamaa the testimony" when he conceals it. The substance of the truffle comes from an earthy vaporous essence that gathers near the surface of the earth through the cold of winter, and is nourished by the rain of spring, so it forms and emerges.Regarding the meaning of "manna" in this context, three views have been given. The first is that it is a type of the manna that was sent down upon Banu Israil, which is the dew that falls upon trees and is gathered and eaten sweet, from which comes tarangubin. The second is that it is from the manna with which Allah favored His servants freely, without any effort or treatment on their part. The third, stated by Khattabi, is that the meaning is not that truffles are a type of the manna sent down upon Banu Israil, for what was sent down upon Banu Israil was like tarangubin, but rather the meaning is that truffles grow without any cultivation or effort.