Is it permissible to take the box of tissues offered by gas stations in Jeddah as a promotional item when fueling for 10 Saudi Riyals?

There is no harm in accepting a gift when filling up with petrol, whether it is a pure gift or part of the contract, because the quantity of petrol and the gift are known. This is supported by analogy with Imam Ahmad's ruling concerning the buyer's handkerchief given to the cloth seller, where the handkerchief becomes an increase in price attached to the contract. It is affirmed that a visible gift attached to the commodity is permissible in Sharia because it is like a reduction in its price.