How convenient is it to find a cure for all ailments in one substance?
I think that would save us a lot of money in health care costs, and would make life more enjoyable. Well, in fact, there is a plant that the prophet of Islam (PBUH) has described as the cure for every disease except death.
Nigella sativa, black cumin, Al-habate Souda, Habate Al-Barakah, “Seed of blessing”, Kalonji in Hindi, or Siyah daneh in Persian, these are all names for the same plant, native to southwest Asia that the Prophet Mohammed exalted its medicinal properties.

The black Seed has been used for medicinal purposes in different cultures and for centuries. In the Islamic tradition, Ibn Sinaa or Avicenna, prescribed the seed as a stimulant for body energy, and helps recovery from fatigue.

Ibn alqayem listed many medicinal uses for the black seed. He mentioned that it helps against all types of cold ailments, increases milk production in nursing mothers, eliminates flatulence, extracts the helminthes (worms), relieves leprosy and phlegm fevers, opens clogs, and decomposes accumulating gas and excess moisture in the stomach. When the black seed is ground, blended with honey and drunk with some warm water, it will dissolve the stones in the kidney and the prostate. When the Black Seed is fried and finely ground, soaked in oil and then drops are administered in the nose, it will help against cold conditions accompanied by intensive sneezing. When it's cooked in vinegar, and then one rinses his mouth with it, it will relieve the symptoms of toothache resulting from sensitivity to cold. When it's inhaled in its powdered form, it will help against water that accumulates in the eyes. When it is used in a bandage while blended with vinegar, it heals spots and exposed skin ulcers and decomposes the acute mucus tumors and hard ones.

So many other benefits of black seed were listed in the book “Prophetic medicine”, but as with any type of medicine, the author warned against excess use. Twenty five grams is the recommended dosage, and consuming the black seed in excess has been known to be deadly.
Modern Science has empirically proved the beneficial properties of the Nigella sativa, its oil has been found to help relieve the symptoms of asthma, bronchitis, and coughing.
There is also ongoing research done on this herb at the Kimmel Cancer center at Jefferson in Philadelphia, headed by Hwyda Arafat, MD, PH D. Early findings “suggest that thymoquinone, an extract of Nigella sativa seed oil, could eventually have some use as a preventative strategy in patients who have gone through surgery and chemotherapy or in individuals who are at a high risk of developing cancer.”
Using the black seed daily would surely prevent a lot of illnesses, fortify your immune system, and energize your body.
Verily, the prophet Mohamed, the truthful, the trustworthy, doesn’t speak in vain. If his teachings were followed by humanity, our souls and bodies would be cured from all disease.

References:

1- http://en.wikipedia.org/wiki/Nigella_sativa

2- http://www.kimmelcancercenter.org/news/2008-05-23_Arafat.html

3- "Prophetic Medecine", Ibn Alqayem Al-jaouezia.