Olive oil

It is narrated from Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said to me: "O Ali! Eat olive oil and apply it (to the body), for whoever anoints himself with olive oil, Satan will not come near him for forty nights."
Al-Harith bin Abi Usamah recorded this hadith in his Musnad; however, its chain contains the narrators Hammad bin Amr and al-Sari bin Khalid, because of whom the scholars of hadith have declared this report severely weak, indeed mawdu' (fabricated).

Salamah bin Abi Salamah narrates from his father, who said: I heard Sayyidah Aishah (may Allah be pleased with her) speaking when olive oil was mentioned in her presence, and she said: "The Messenger of Allah (peace and blessings be upon him) used to order that (olive oil) be eaten and applied (to the body) or used for massage, and he would say: 'Indeed, it is (obtained) from a blessed tree [Surah al-Nur: 35].'"
The chain of this hadith contains the narrator Muhammad bin Umar al-Waqidi, who is da'if (weak) and matruk (abandoned) according to the majority of hadith scholars; however, there are other sahih and hasan hadith on the use and virtue of olive oil (e.g. Sunan al-Tirmidhi: 1851) that strengthen its meaning.