Buying
      with debit cards
Question

                I hope that you will beable to
      advise us about using Saudi Net cards [debit cards] when buying things
      that we need from the stores. These cards are used in the following
      manner: when the amount of the purchase has been added up, for example 150
      riyaals, the card is given to the vendor and he passes (“swipes”) it
      through a machine that he has in his store. The value of the purchase is
      then taken instantly, by transferring the amount from the purchaser’s
      account to the vendor’s account in the same instant, i.e., before the
      buyer leaves the shop.
Praise be to Allah.If the matter is as you describe, there is no reason why these cards
      should not be used, if the purchaser has sufficient funds in his account
      to cover the required amount.
 And Allaah is the source of strength. May Allaah bless our
      Prophet Muhammad and his family and companions, and grant them peace.