Promise and vow

Q: In order for a promise with Allah to be valid does the promise have to be said verbally, and what if a person doesn't say it verbally but just says it in his head?

Girl taking bay'at with a shaikh

Q: I wanted to seek you ulama's opinion with regards to an unmarried girl doing bai'at with a sheikh to do tazkiya of nafs. She is a girl studying online Aalimah course. Nowadays we can do bai'at by staying in our home itself via live program of any bai'at majlis, so no issue of hijab arises. But I wanted to know is it good to have bai'at with a sheikh for a woman, or she can do azkaar that are reported in ahadith shareef by her own without guidance of a sheikh? Hoping for a convincing advise.

Changing one's name

Q: My name is Asad. At times I feel depressed of my wrong and think that I am actually an "Asad of my nafs or an "Asad of sin." However, I want to be an Asad of Allah Ta'ala. Please advise if it would be appropriate to change my name to 'Asadullah.'