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.
The fulfillment of vows is one of the attributes of the righteous servants of Allaah Almighty. Praising them in the Quran, Allaah says (what means):
• {They [are those who] fulfill [their] vows and fear a Day whose evil will be widespread.} [Quran 76: 7]
• {Then let them end their untidiness and fulfill their vows.} [Quran 22: 29]
Making a vow to spend money in charitable purposes is binding. There is no doubt that our brothers in Palestine are in need of our support and assistance. They are eligible recipients of Zakah, charity, and vows. When one makes a vow to give something to a certain person, it is binding that he gives that thing to that very person. The scholars even said: "When one makes a vow to give something to a certain person and then he declines, the recipient has the right to demand it from him."
Consequently, you are required to fulfill your vow and give the money to the Palestinian people.
Maintaining kinship ties, on the other hand, is a great virtuous action that involves a great deal of good. So, if you can give them whatever you can offer other than the vow you made, then your action will be rewardable and commendable. But if you cannot, then you are blameless. Allaah does not charge a soul of doing what is beyond its capacity.
Allaah Knows best.