Suppose that I made a vow (Nadhr) to do something daily and I could not do that for five days. Do I need to expiate five times for that? Or is one expiation enough? And is the same ruling apply on an oath (Yameen)?

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger. 

First of all, it should be mentioned that if the vow (Nathr) is to do an act of obedience to Allah, then it must be fulfilled, as the Prophet said, "Whoever vows to obey Allah, let him obey Him, and whoever vows to disobey Allah, let him not disobey Him." [Al-Bukhaari]

If the vow is timed (to be fulfilled at a particular time), then it is not permissible to delay it beyond that time without a valid reason. If he delays it for a valid reason, such as sickness and the like, then he is not sinful and is not obliged to expiate for that. However, he must hasten to make up for it whenever he becomes able to do so.

If he delays fulfilling the vow without a valid reason, he is sinful and is obliged to make up for it.

The scholars differed in opinion whether, in addition to this, he is obliged to expiate because of the delay in fulfilling his vow or not. The Hanbali School held that he is obliged to expiate, while the majority of scholars held that expiation is not obligatory. The Hanafi School has a detailed ruling in this regard.

The view that we hold as preponderant and adopt at Islamweb is the view of the majority of the scholars: that expiation is not obligatory because there is no authentic text that indicates the obligation of expiation in this case.

If he made a vow to do that act of worship every day, like someone who vowed to give charity or recite a portion of the Quran every day, then he must fulfill the vow every day. The vow is not invalidated by not fulfilling it one day or several days. Rather, he has to make up for whatever he missed and continue to fulfill the vow at its appointed time in the remaining days.

As regards the oath (Yameen), whoever swears to do something at a certain time and does not do it, then he has broken his oath. It is known that if someone broke an oath, he is obliged to expiate for it. The expiation for breaking an oath is mentioned in the verse in which Allah says (what means): {So its expiation is the feeding of ten needy people from the average of that which you feed your [own] families or clothing them or the freeing of a slave. But whoever cannot find [or afford it] - then a fast of three days [is required]. That is the expiation for oaths when you have sworn. But guard your oaths.} [Quran 5:89]

The repeated breaking of an oath sometimes leads to an expiation for every time that one broke the oath, and sometimes the expiations overlap and only one expiation is enough, according to the nature of the oath; whether he made one single oath regarding many actions, or he made many oaths regarding one single action, or he made many oaths regarding different actions.

If a person makes an oath to give charity every day or to recite a portion of the Quran every day, then his oath is not invalidated by breaking his oath the first time; rather, he breaks the oath every time he does not give charity or does not recite the Quran, because the expression ‘every day’ necessitates the repetition of breaking the oath.

Ibn ‘Arafah said, "Breaking the oath invalidates it, so there is no repetition of what breaking the oath necessitates by the repetition of breaking it except if the oath contained a wording or an intention or a custom that indicates repetition. An example of a wording is to say: 'every time' or 'whenever.'"

The Maaliki Fiqh book Al-Kharashi ‘ala Mukhtasar Khaleel reads about the statement of the author "and it (expiation) is repeated if he intended to repeat breaking the oath":

"....if the oath involved a customarily repeated action, then breaking the oath is repeated every time he fails to fulfil that action. For instance, if someone makes an oath not to abandon the Witr prayer as long as he is in Makkah, then his breaking of the oath is repeated by the repetition of abandoning the Witr prayer. This is because the custom entails repetition. It is as if he had said: 'Whenever I abandon the Witr, I have to expiate.' Similar to the Witr prayer is any act of worship that has a specified time at which it is to be performed; it neither precedes it nor is delayed beyond it, and it is permanent."

For more benefit, refer to fatwas 119549 and 138168.

According to the view which we adopt at Islamweb, repeated breaking of the oath requires one expiation only as long as the oath was made regarding one thing and the one who made the oath did not expiate when he broke it the first time. 

Allah knows best.