Fatwa ID: 04382
Answered by: Alimah Nasima Umm Hamza
Assalamualaikum Ustadh, hope you're well in sha Allah (swt).
I wanted to ask that if someone asks me to buy an item for them, but they don't give me the money for it and they don't know the price, hence I go and buy it (for example, a book costing £10 and I get given it for £8 because of student discount). Thereafter, I sell it to that person for the original price, is that allowed?
بِسْمِ اللهِ الرَّحْمنِ الرَّحِيْم
In the name of Allah, the Most Gracious, the Most Merciful
The type of transaction you are describing is a muraabahah transaction.
A muraabahah transaction is also known as a cost-plus profit transaction. In order for this transaction to be Islamically valid, you must make the cost price of the item known to the buyer. Therefore you must inform them how much you will buy it for and you must both agree to the price the buyer will pay from you.
Therefore, it will not be permitted for you to hide your cost price from the buyer.
Only Allah knows best
Written by Alimah Nasima Umm Hamza
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 Al-Marghinani, Al-Hidayah, Volume 3, Page 56