Is the aforementioned vow considered obligatory, or is expiation permissible for it?

This vow is among the permissible vows, which do not involve an act of worship. The majority of scholars hold that it is not binding and its fulfillment is not obligatory, nor is there expiation for abandoning it, due to the Prophet's (PBUH) saying: "There is no vow except in what is sought for the sake of Allah." Whereas Imam Ahmad holds that it is binding and valid, and one is given the choice between fulfilling it or abandoning it, and its expiation is like the expiation for an oath.

The more cautious approach, though not obligatory, is for the questioner to offer expiation for an oath, thereby avoiding the dispute. The expiation for an oath is feeding ten poor persons, or clothing them, or freeing a slave; and if one cannot find [the means], then fasting for three days, as stated in verse 89 of Surat Al-Ma'idah.