Is it permissible to take money in advance from several people to buy olive oil for them, and sell it to them at a price higher than the market price after adding a profit margin in exchange for its quality, knowing that the market price is 7 dinars per kilogram, and I will sell it for 8 or 9 dinars?

The transaction mentioned is valid if it is a salam (forward) sale that fulfills its conditions, among them the full payment of the price at the time of the contract.

However, there are two issues: The first is the ambiguity of the price in the statement: "I will sell you the kilogram for (9) or (8) dinars," so it must be specified.

The second: Oil is a measured commodity, and there is a difference of opinion regarding the validity of salam in measured commodities by weight, although the majority view is that it is valid.