What is the ruling on Vodafone's "Shukran Salefny" (Lend me, Thank you) service, where it lends the customer 2.5 EGP of call credit and deducts 3 EGP upon the next top-up, considering the remaining half EGP as a fee for the service?

This service, called "Sallifni Shukran" (Lend me, Thank you), is not a case of a loan drawing a benefit. Rather, it is the sale of a deferred service for a price greater than its cash price. If the repayment period is specified, there is no harm in it, because what matters are the meanings, not the wordings. However, if the repayment period is unknown, the contract is void due to the uncertainty of the term, and it is impermissible to enter into void contracts.