I said to Ibn ‘Abbas, “The people are narrating that the Prophet said, ‘Take a bath on Friday and wash your heads (i.e. take a thorough bath) even though you were not Junub and use perfume’.” On that Ibn ‘Abbas replied, “I know about the bath, (i.e. it is essential) but I do not know about the perfume (i.e. whether it is essential or not.)
Ibn ‘Abbas mentioned the statement of the Prophet regarding the taking of a bath on Friday and then I asked him whether the Prophet (p.b.u.h) had ordered perfume or (hair) oil to be used if they could be found in one’s house. He (Ibn ‘Abbas) replied that he did not know about it.
Ibn ‘Abbas did not know about it, but it’s clearly mentioned in Salman Farsi’s Hadith that wearing oil (in one’s hair) and perfume are among the Sunnahs of Friday. This is the Hadith:
Volume 2, Book 13, Number 706:
The Prophet (p.b.u.h) said, “Whoever takes a bath on Friday, purifies himself as much as he can, then uses his (hair) oil or perfumes himself with the scent of his house, then proceeds (for the Jumua prayer) and does not separate two persons sitting together (in the mosque), then prays as much as (Allah has) written for him and then remains silent while the Imam is delivering the Khutba, his sins in-between the present and the last Friday would be forgiven.”
Allah’s Apostle was asked regarding ghee (cooking butter) in which a mouse had fallen. He said, “Take out the mouse and throw away the ghee around it and use the rest.”
Ghee is more viscous than the usual oil, so it can be used after throwing away the part touched by the mouse. Going into the scientific details, ghee allows less diffusion so the impure particles of the mouse won’t be able to travel very far. Oil, however, would have to be thrown away if a mouse fell in it.