Olive Oil.

Allah the Almighty speaks of the olive in the Holy Qur’an;

“...Lit from a blessed tree, an olive, neither of the East [so that it only gets the sun’s rays in the morning], nor of the West [so that it only gets the sun’s rays in the afternoon, instead it is exposed to the sun all day long], whose oil would almost glow forth (of itself), although no fire hath touched it.” 
[24:35]

And also;

"By the Fig and the Olive."
[95:1]

It was narrated by 'Umar (radhi Allahu anhu) that he heard the Messenger of Allah (sallallahu alayhi wasallam) say, "Season (your food) with olive oil and anoint yourselves with it, for it comes from a blessed tree."

Sunan Ibn Majah Book 29, Hadith 3444. Graded as Sahih by Darussalaam.

http://www.sunnah.com/urn/1274270

Since olives and their oil are mentioned in both the Qur'an and the Sunnah respectively, they are considered one of the primary healing foods and are therefore recommended to be consumed regularly.

The healing power of olive oil comes in part from its high levels of Mono-unsaturated fatty acids and antioxidants, and in part from the fact that it is well tolerated by the stomach, so it easily breaks down and is an excellent protective emollient for stomach ulcers and gastritis.

All kinds of olive oil are beneficial for softening the skin and slowing down both the skin aging and hair greying processes. It is also known as an anti-inflammatory and beneficial for all kinds of liver and gall bladder problems.

Studies have shown that people who consume around two tablespoons of extra virgin olive oil daily have a lower level of LDL cholesterol in the blood, leading to a lower overall risk of heart disease. Spanish researchers have also found links between olive oil and a reduction in the occurrence of both colon cancer and breast cancer.

The best possible type of olive oil to buy is cold-pressed extra virgin olive oil, which is greenish in colour and contains the highest possible levels of Vitamin E, antioxidants and phenols. This is because it is less processed than commercially refined olive oils. Olive oil is best kept tightly sealed in a cool dark place, as exposure to the air and a light, warm position promotes faster rancidity. Olive oil should be used in place of regular cooking oil in pasta dishes, sauces, stews and curries.

The brine in which olives are bottled is particularly beneficial for strengthening in the gums if used as a mouth rinse.

It is encouraged to use Olive Oil regularly as a moisturiser for the skin and hair.

The use of oil on the body can be traced directly to the Sunnah, where our Mother A'ishah (radhi Allahu anha) also narrated that "The Prophet (sallallahu alayhi wasallam) used to (put) bend his head (out) to me while he was in Itikaaf in the Mosque during my monthly periods and I would comb and oil his hair."

Sahih al Bukhari Volume 3, Book 33, Number 245

Olive oil is great for hair and over time, makes it shiny and silky and easy to manage. It's recommended to massage the scalp with your fingertips when applying olive oil so that its antioxidants are absorbed with greater ease. Olive oil is also used for hair loss, hair strengthening (prevention of split ends) and slowing down the rate of grey hair.

Olive oil is also used by Raqi's when they recite the Qur'an by Allah's Leave for people who are afflicted by sorcery. In sha Allah there is no harm in reciting the Qur'an on olive oil before using it.