If a person vows to keep a fast but does not specify when and for how long, in the event that he fasts for one day, it is sufficient. If he vows to perform prayers but does not specify how many prayers or their particulars, in the event that he performs a single two-unit (rakʿah) prayer or the witr prayer,[4] it is also sufficient.
If he vows to give alms to the poor but does not specify the type of thing he will give or its quantity, in the event that he gives something about which it could be said, ‘He has given alms to the poor’, he will have fulfilled his vow. If he vows to do something for the sake of Allah the Exalted, then in case he performs one prayer, fasts for one day, or gives something to the poor as alms, he will have fulfilled his vow.