Musnad Ahmad 1017:4

Aswad ibn Amir narrated to us, Zuhayr narrated to us, from Wasil ibn Hayyan al-Bajali, Abdullah ibn Buraydah narrated to me, from his father, from the Prophet, peace and blessings of Allah be upon him, who said: "The truffle is a medicine for the eye, and the Ajwa is from the fruits of Paradise, and this black seed—Ibn Buraydah said: meaning the Nigella sativa (shuniz) which is in the salt—is a medicine for every disease except death."