What is the ruling on a vow that I made but was unable to fulfill due to financial incapacity, and will I be afflicted with problems because of it, and what is its expiation?

A vow of qurbah (an act of devotion intended to bring one closer to Allah) must be fulfilled. Giving a gift is among the praiseworthy acts of qurbah. Therefore, the vow to give a gift must be fulfilled if you are able to present it. If you become unable to fulfill your vow due to an inability that is not expected to cease, then you must offer an expiation for an oath (kaffarat yamin): feeding ten poor persons, or clothing them, or freeing a slave. If you cannot find any of these, then fasting for three days. Whoever deliberately fails to fulfill their vow while being capable of it exposes themselves to punishment.