Is it obligatory to fast 21 days for the entire week, or three days for Friday only, as expiation for breaking an oath not to practice masturbation during the seven days of the week, then practicing it on Friday, given the unavailability of money for feeding or freeing a slave?

If a person takes a single oath and then breaks it, only one expiation is required of him, even if the act sworn upon is repeated. This is because the oath is dissolved by the first breach. However, if the one who swore intended the expiation to be repeated, or if his wording indicated it—such as his saying, "Every time I do such and such"—or if custom necessitated it, then the expiation multiplies. The expiation for an oath is to feed ten poor people, or clothe them, or free a slave. If one cannot find these, then it is to fast for three days.