Vowed to offer a gift to the poor, is it permissible to give its value to a poor, sick person?
4-8-2015 | IslamWeb
Question:
If I vowed to offer a gift to the poor in a certain manner and then found out that there is a poor, sick person who needs help, may I offer the value of the vow to this sick person? Is this impermissible given that the two matters are irrelevant? Is it impermissible to change the vow?
Answer:
All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
If you mean that you took a certain vow in which you did not specify its beneficiary and then knew about the sick person and wanted to give him the value of the vow because he did not need the very thing which you vowed to offer, then the answer is that the Muslim should fulfill his vow according to the manner in which he took his vow and give the object of the vow to the beneficiary that he specified.
Therefore, it is impermissible for you to offer the value of the vow that you allotted to that sick person or to any other person (that was not intended in the vow). Rather, you should offer it exactly in the way that you vowed. Some people of knowledge viewed that it is permissible to offer the value instead of the object of the vow.
If you mean that you have vowed to offer a gift to specific poor people, then these poor people become the owners of the vowed object once you specified them as the beneficiaries of the vow and it is impermissible for you to give it to any other person.
Al-Haytami, a Shafi‘i scholar 
said in the explanation of Al-Minhaj: “If one says: ‘I have to give twenty dinars in charity to so-and-so’, or, ‘if my sick loved one is cured, I have to offer such-and-such’, and he is then cured, then the beneficiary owns it, even if he has not already received it.”
However, if there is no specification and the vow is dedicated to poor people due to their having the characteristic of being poor, then it is permissible. Rather, it is preferable to give it to the poor, sick person because he is characterized with being poor and, besides that, is also sick and needy.
Allaah Knows best.