Kaffarah for breaking an oath

Q: My mother swore that my younger sister would not marry before me out of pity, but this was done with the mother's permission. What should my mother do regarding the breach of her oath?

A: If the case is as you have mentioned, your mother must offer a Kaffarah (expiation) for breaking her oath, (Part No. 23; Page No. 102) which is feeding or clothing ten Miskins (needy people) or freeing a believing slave. If she cannot afford any of them, she must observe fasting for three days.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.