Musnad Ahmad 30:3495

Rawh narrated to us, Muhammad ibn Abi Hafsah narrated to us, he said: Ibn Shihab narrated from Sa'id ibn al-Musayyib, from Abu Hurayrah, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "You must use this black seed, for it is a cure for every disease, except for the *sam*." He said: Ibn Shihab said: [The *sam* is] death.