Imam Abu Nu’aym (rahimahullah) has recorded the following narration in At Tibbun Nabawi: Sayyiduna Abu Hurayrah (radiyallahu ‘anhu) reported that Rasulullah (sallallahu ‘alayhi wa sallam) said: “Eat olive oil and apply it as oil for it has cure from seventy illnesses including leprosy.” (At Tibbun Nabawi, Hadith: 684)

 Shaykh Ahmad Siddiq Al Ghumari, a Moroccan Scholar of the recent past has declared this version of the Hadith a fabrication. (Refer: Al Mughir, Hadith: 354. Also see: At Taysir Bi Sharhil Jami’is Saghir, vol. 2 pg. 221 and As Sirajul Munir, vol. 3 pg. 100)

2. This is part of a lengthy narration wherein Nabi (sallallahu ‘alayhi wa sallam) offered numerous advices to Sayyiduna ‘Ali (radiyallahu ‘anhu). The part in question is as follows: “O Ali! Apply olive oil and use it in your gravy for certainly Shaytan does not come close to the person who applies olive oil for forty nights”. (Musnadul Harith; Bughyatul Bahith, Hadith: 469)

However, this Hadith has been transmitted with an extremely weak chain. In fact Imam Bayhaqi (rahimahullah) has declared the Hadith a fabrication. (Dalailun Nubuwwah, vol. 7 pg. 229, Al Matalibul ‘Aliyah, Hadith: 77. Also see: Al La-Alil Masnu’ah, vol. 2 pg. 312)

Note: The first part of the Hadith “Eat olive/olive oil and use its oil” has been recorded in other Hadith collections and is suitable to quote. Although the Hadith in question isn’t suitable to quote, we are still encourage to use olive oil in other Hadiths.

 And Allah Ta’ala Knows best.

https://hadithanswers.com/the-hadith-regarding-olive-oil-being-a-cure-for-seventy-illnesses/

https://hadithanswers.com/will-applying-olive-oil-protect-one-from-shaytan/