Musnad Ahmad 30:169

Sufyan narrated to us, from al-Zuhri, from Abu Salamah—if Allah wills—from Abu Hurairah, from the Prophet, peace and blessings of Allah be upon him: "You must use this black seed, for indeed in it is a cure for every disease, except the *sam*." Sufyan said: "The *sam* is death, and it is the *shuniz* (black cumin/nigella sativa)."