The Prophet of Allah ﷺ said, "Truffles are from the manna, and their juice is a cure for the eye."
حدثنا معتمر بن سليمان قال سمعت عبد الملك بن عمير عن عمرو بن حريث
أن نبي الله ﷺ قال الكمأة من المن وماؤها شفاء للعين
Its isnad is sahih. Mutamir bin Sulayman bin Tarkhan Taymi is trustworthy and truthful.Truffles (al-kamah): a whitish, fat-like plant that grows from the earth, also called "the fat of the earth." Al-kamah is a plural, and its singular is kamah, though this goes against the normal grammatical pattern, since the usual rule would be the reverse. This is stated in Nihayah, and it is considered one of the anomalous forms."From the manna" (min al-mann): in Nihayah it is explained that this means it is something with which Allah favors His servants. It has been said that it is likened to manna, which is the sweet honey that descends from the sky freely, without any labor. Likewise, truffles require no effort, neither planting nor watering.This hadith was narrated by Muslim (2:143–144) and Tirmidhi (3:170), and it was also narrated by Bukhari, Nasai, and Ibn Majah, as mentioned in the commentary on Tirmidhi.