The Messenger of Allah ﷺ said, "In the black seed there is a cure for every disease except as-sam."They asked, "Messenger of Allah, what is as-sam?"He replied, "Death."
حدثنا يزيد ويعلى قالا حدثنا محمد بن عمرو عن أبي سلمة
أن رسول الله ﷺ قال في الحبة السوداء شفاء من كل داء إلا السام قالوا يا رسول الله وما السام قال الموت
Its isnad is sahih, and it has already appeared as 7285, from the narration of Zuhri from Abu Salama, in similar wording, where the tafsir of "saam" was given there as Zuhri's own words, but here in this narration it is explicitly raised, being from the Prophet's ﷺ own statement.