Wudhu

Doubts regarding the validity of wudhu when one has an oily face

Q: My face is oily. When I am performing wudhu, some of the oil of my face gets onto my hands. Do I have to rub my hands with water to ensure that water gets underneath the oil and reach my skin?

Do I have to rub any part of my body if the oil of my face gets onto them (for example my forearms, my feet)?

In that same logic, if oil from a part of my face (the left part for example) get onto or mixes with the oil of another part of my face (the right part for example) do I have to rub that area with water (the right part of my face)? 

Making wudhu with compression stockings

Q: An old lady has been advised by a doctor to wear compression stockings on her legs for circulation. She doesn't have any wounds etc. on her legs. The stockings are from her knees and only the toes are open.

The stockings are very tight and she requires someone to put it on and remove it for her. Is it permissible for her to make masah over the stockings and only wash the toes for wudhu?

Washing the face in wudhu

Q:

1. When the boundaries of the face are mentioned in the books of Fiqh, are the boundaries included in the washing i.e. is the bottom of the chin included and must be washed?

2. If someone came and said to you, "I can’t see the bottom part of my nose (just above the moustache) so must it be washed? What would you say to him when telling him about the definition of the face?

Repeating salaah if one found out that wudhu was not valid

Q: I was sitting after performing salaah when I noticed that there is a black, sticky substance on my foot through which water could not pass. It was the size of a whole round fingernail, and I had not seen it before.

Then, my brother told me that he saw it since 3 or 4 days on my foot. I had also led jamaat during these days. Will I have to repeat all the salaah that I had offered on these days? Will those who followed me in jamaat also have to repeat their salaah?