The World Federation One Stop Fiqh

Ruling 2687

If a person takes an oath to do something or to refrain from doing something – for example, he takes an oath to keep a fast or to stop smoking – then in the event that he intentionally (ʿamdan) does not fulfil his oath, he will have committed a sin and he must give recompense (kaffārah). That is, he must either free a slave, or feed ten poor people (fuqarāʾ), or clothe them. And if he cannot do any of these, he must fast for three consecutive days.