fails to observe it, he must make it up; should sickness overtake him, the obligation is waived. The same concession applies to a menstruating woman—she is not required to make up the days that coincide with her menses.
Anyone who vows to fast a specific month must fast from one crescent sighting to the next, without counting the days. If he begins without reference to the crescent phases, he should fast thirty days.
Whoever vows to fast without fixing a number fulfils the vow with a minimum of a single day.
Anyone who vows to perform a prayer is bound to carry it out. If he states neither a number of cycles nor a particular intention, the least that fulfils the vow is two rakʿahs (units of prayer).
If a person vows to fast on the Day of Fitr or the Day of Adḥā, it is impermissible for him to do so because the Prophet ﷺ forbade fasting on those days. He must eat, and no make-up is required, for no vow can oblige a sin. The same ruling applies to one who vows to fast during the days of tashrīq: he must break his fast and no make-up is due. A report from Mālik that he should later make it up for both is unsound. Mālik’s established view concerning the third day of tashrīq is that whoever vows to fast it must indeed fast it. A detailed discussion of vow-fasts has already been given in the Book of Fasting.
Whoever vows to give all his wealth in charity is liable only for one-third of it. According to Mālik, the same limitation applies to someone who swears an oath to give his wealth in charity and then breaks it: he must surrender only one-third. Rabīʿah and Ibn Abī Salamah held that one-fortieth of his wealth suffices. Ibn Wahb said: if the oath-taker is affluent, one-third of his wealth suffices, as Mālik said; if he is of moderate means, paying his zakāt purifies his property, as Rabīʿah said; and if he is poor, the expiation for breaking an oath is enough.
Ibn ʿUmar maintained that whoever breaks such an oath must give all of his wealth. ʿĀʾishah, together with a group of Companions and Successors, held that the expiation for breaking an oath is sufficient.
If a person vows to give away everything he will ever earn, nothing is incumbent upon him unless he fixes a term that, on average, he can expect to reach in his lifetime; in that case he must give one-third of what he earns. Whoever vows to give a specific item from his property in charity is obliged to give that very item.