What is the ruling on someone who has broken his oath more than once not to commit a sin; is he required to offer a single expiation or multiple expiations, and is it permissible for him to observe voluntary fasting if he is unable to offer the expiation for the oath except by fasting?

If a person takes a single oath and then breaks it, only one expiation (kaffarah (definition)) is required of him, unless he intended for the expiation to be repeated with the repetition of the breaking of the oath. So, whoever vows to abandon a sin and then commits it, only one expiation is required of him, even if he repeats the sin, because his oath was dissolved by the first act. It is obligatory to hasten to perform the expiation for the oath immediately upon breaking it, and it is not permissible to delay it or to observe voluntary fasting before performing the expiation.