What is the ruling on expiation for not fulfilling a vow to feed a cat when there is extra food available, and what are the consequences of forgetting to renew the intention to feed it for the sake of Allah, and does this vow remain binding after marriage and leaving the home?

This pledge differs in its ruling, and the most cautious view is that it is a vow if the intention behind it is obedience. However, a vow is not binding with food charity or feeding a cat from it, because it is owned by the father. The Prophet, peace and blessings be upon him, said: "There is no vow upon a man concerning what he does not own," and "There is no fulfillment for a vow that involves disobedience, nor for what a servant does not own." Therefore, you are not bound by anything with this wording, and you must seek permission from your parents before feeding the cat.